[MINOR] Fix flaky TestHoodieAvroDataBlock

[wombatu-kun]

Change Logs

Recently i faced this failure:
Error: TestHoodieAvroDataBlock.testGetRecordIteratorWithInputStream:188->verifyRecords:360 Record count mismatch ==> expected: <0> but was: <1000>
That happened because of unnecessary random value generation in selectRandomRecords: as a number of selected records was randomly generated 0 value, so it returned an empty list recordsForFilter (and keysForFilter). Later, when we call dataBlock.getRecordIterator with empty list as keysForFilter, it returns all records, and it causes records verification to fail.

This PR fixes it by not using Random for generating number of selected records, just use value allRecordsNum/4.

Impact

fix flaky test

Risk level (write none, low medium or high below)

none

Documentation Update

none

• The config description must be updated if new configs are added or the default value of the configs are changed
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Contributor's checklist

• Read through contributor's guide
• Change Logs and Impact were stated clearly
• Adequate tests were added if applicable
• CI passed

[hudi-bot]

CI report:

• c9c8b39 Azure: SUCCESS

Bot commands

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• @hudi-bot run azure re-run the last Azure build

[voonhous]

Removing release-1.0.2 tag for this as this PR is dependent on !11924