Allow configuring kafka producer max.message.size

[francoisferrand]

• Allow configuring kafka producer's max request size
• Properly validate oplogPopulator params
• Remove conf/Config.js, not used in 8.x branches

kafka producer max request size used to be hard-coded in backbeat, even though it is closely linked to a server setting hard-coded in ZKOP.
Goal is now to make it configurable in backbeat, so that ZKOP can propagate the value everywhere and make it configurable via CR.

Note that we do not propagate the value to individual kafka-connect connectors: ZKOP will instead set the default values for all connectors in the kafka-connect cluster.

Issue: BB-436

[bert-e]

Hello francoisferrand,

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[bert-e]

Integration data created

I have created the integration data for the additional destination branches.

• this pull request will merge improvement/BB-436 into
  development/8.6
• w/8.7/improvement/BB-436 will be merged into development/8.7

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• development/7.10
• development/7.4
• development/7.70
• development/8.5

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[bert-e]

Waiting for approval

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• the author

• 2 peers

[francoisferrand]

/approve

[bert-e]

In the queue

The changeset has received all authorizations and has been added to the
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The changeset will be merged in:

• ✔️ development/8.6

• ✔️ development/8.7

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• development/7.10
• development/7.4
• development/7.70
• development/8.5

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[bert-e]

I have successfully merged the changeset of this pull request
into targetted development branches:

• ✔️ development/8.6

• ✔️ development/8.7

The following branches have NOT changed:

• development/7.10
• development/7.4
• development/7.70
• development/8.5

Please check the status of the associated issue BB-436.

Goodbye francoisferrand.