[exporter/datadog] Add configurable reporter_period for host metadata (…

…open-telemetry#36451)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

This pull request introduces a new configurable parameter
`reporter_period` for the Datadog exporter’s host metadata
configuration. This enhancement allows users to specify the frequency at
which host metadata is sent to Datadog. The changes span multiple files
and include updates to configuration, factory methods, and test cases.

Enhancements to Datadog exporter:

*
[`.chloggen/add-configurable-reporter-period-for-host-metadata.yaml`](diffhunk://#diff-e3e3c57c49d2a921abc8470bccafabf4d632b0dc142eb3e95b3b6fac57107a11R1-R27):
Added a changelog entry for the new `reporter_period` parameter.
*
[`exporter/datadogexporter/examples/collector.yaml`](diffhunk://#diff-766be9823b8ec8b8de17e2c6c785d9f93e13b5a7e84ff441040077ab5e726a79R452-R456):
Added documentation for the new `reporter_period` parameter in the
example configuration file.
*
[`exporter/datadogexporter/factory.go`](diffhunk://#diff-c9e9f39ffda08a2af74c0d54d37f21e14cdb95c4136cdbe238de6be2bfe31389L127-R125):
Updated the factory to use the `reporter_period` from the configuration
instead of a hardcoded value.

Configuration updates:

*
[`exporter/datadogexporter/internal/hostmetadata/config.go`](diffhunk://#diff-0c9f0862d61390add366aca3e30834a1e01f16a3865ef9aca61831cad3459f53R31-R32):
Added `ReporterPeriod` to the `PusherConfig` struct.
*
[`pkg/datadog/config/config.go`](diffhunk://#diff-747858d4c8fea28a92227df09f17ebee01df63dad04812ac5d30a392c9970b73R136-R139):
Added validation for the `reporter_period` to ensure it is a positive
duration and set a default value.
[[1]](diffhunk://#diff-747858d4c8fea28a92227df09f17ebee01df63dad04812ac5d30a392c9970b73R136-R139)
[[2]](diffhunk://#diff-747858d4c8fea28a92227df09f17ebee01df63dad04812ac5d30a392c9970b73R347)

Test case updates:

* `exporter/datadogexporter/factory_test.go`,
`exporter/datadogexporter/logs_exporter_test.go`,
`exporter/datadogexporter/metrics_exporter_test.go`,
`exporter/datadogexporter/traces_exporter_test.go`: Updated test cases
to include the new `reporter_period` parameter.
[[1]](diffhunk://#diff-c50b6d1f06d62a58b6422f3218526437c16554faa2b7fc8eee1d32c021f00ca4R311)
[[2]](diffhunk://#diff-94f5b0119d06dbcfee20cd9b99a104ef208e027c166c463321670a5197e83714R233-R235)
[[3]](diffhunk://#diff-005adb1774d2a402bdd7adf3b6aa150117bf6b3c0bb634bf2c68c6b33f0ce1b5L61-R63)
[[4]](diffhunk://#diff-c19daad040b7310787c0012e5c660dc18a07ba16036d0eaa31a0e18c551d0ef3R148-R150)
*
[`pkg/datadog/config/config_test.go`](diffhunk://#diff-d3a3c19e78bbac07597c6210b4d051f4678df2752e06c82d0f040c52207c5970R97-R105):
Added test cases to validate the `reporter_period` configuration.
[[1]](diffhunk://#diff-d3a3c19e78bbac07597c6210b4d051f4678df2752e06c82d0f040c52207c5970R97-R105)
[[2]](diffhunk://#diff-d3a3c19e78bbac07597c6210b4d051f4678df2752e06c82d0f040c52207c5970R186-R197)
<!-- Issue number (e.g. open-telemetry#1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes open-telemetry#36450

<!--Describe what testing was performed and which tests were added.-->
#### Testing

<!--Describe the documentation added.-->
#### Documentation

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.chloggen/add-configurable-reporter-period-for-host-metadata.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: datadogexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add a configurable `reporter_period` parameter to the Datadog exporter’s host metadata configuration to allow users to specify the frequency at which host metadata is sent to Datadog.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [36450]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []