Fix checks using waitmax and run_cached in Linux agent

[sparunakian]

General information

Since checkmk 2.2, some checks (like chrony) are not returning any data and are presumed missing/vanished. This is due to a regression.

Bug reports

checkmk 2.2.0p7 installed on Debian 12
checkmk Linux agent 2.2.0p7, over SSH, on Debian 12 (but other Linux distributions are affected.)
chrony on the monitored servers

There is no step to reproduce the bug, it appears immediately.

The use of both run_cached and waitmax in some agent sections is causing this. On servers with the timeout binary, waitmax is defined as a function calling timeout In the run_cached function a subshell is started and the waitmax function is not known in this context. If there is no waitmax binary on the system, the check silently fails.

In the 2.1 version of the agent, there was export -f waitmax just after the definition of the waitmax function, allowing it to be callable in the subshell started in the run_cached function.

Proposed changes

This MR reintroduces the missing export.

[github-actions]

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[sparunakian]

recheck

[sparunakian]

I have read the CLA Document and I hereby sign the CLA or my organization already has a signed CLA.

[TimotheusBachinger]

Dear Checkmk Contributor! Unfortunately, we had to re-write our git-repo history, rendering your PR auto-closed. We will therefore rebase your PR onto the current master and reopen it again. Sorry for the inconvenience.

[TimotheusBachinger]

Dear Contributor. Unfortunately, we learned that re-opening a PR which was force-rebased, is not possible (see isaacs/github#361). Therefore we kindly ask you to create a new PR for your change. We apologize for the circumstances and will implement technical measures to prevent such incidents in the future.