[BUGFIX][v1.x] Fix a bug for 1bit quantizer

[shuo-ouyang]

Description

Fix a bug for encoding parameters in gradient_compression.cc, which may lead to inconsistent threshold on worker and server when using 1bit quantizer (if the threshod is set to a non-zero value).

releated pr: #17952

Checklist

Essentials

• PR's title starts with a category (e.g. [BUGFIX], [MODEL], [TUTORIAL], [FEATURE], [DOC], etc)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage
• Code is well-documented

Changes

• Feature1, tests, (and when applicable, API doc)
• Feature2, tests, (and when applicable, API doc)

Comments

• If this change is a backward incompatible change, why must this change be made.
• Interesting edge cases to note here

[mxnet-bot]

Hey @shuo-ouyang , Thanks for submitting the PR
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[shuo-ouyang]

@mxnet-bot run ci [centos-cpu, unix-cpu]

[mxnet-bot]

Jenkins CI successfully triggered : [unix-cpu, centos-cpu]

[shuo-ouyang]

@mxnet-bot run ci [unix-cpu]

[mxnet-bot]

Jenkins CI successfully triggered : [unix-cpu]