[202211][db_migrator] Add migration of FLEX_COUNTER_DELAY_STATUS during 1911->2211 upgrade + fast-reboot. Add UT.

[vadymhlushko-mlnx]

What I did

Add migration of FLEX_COUNTER_DELAY_STATUS attribute of config_db FLEX_COUNTER_TABLE during the SONiC to SONiC upgrade + fast-reboot from older versions 201911 -> 202211.

This change is required for the fast-reboot procedure because without it the counters will be created during the init flow which will waste a lot of resources and cause data plane degradation of more than 30 seconds.

How I did it

Modify the db_migrator.py.

How to verify it

Add UT.

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[keboliu]

@vaibhavhd would you please help to review?

[vaibhavhd]

Why is this change not needed on master?

[keboliu]

@vadymhlushko-mlnx please resolve the checker issue so we can proceed.

[vadymhlushko-mlnx]

Why is this change not needed on master?

The PR's for other branches have already been created:

#2839
#2870
#2869

[keboliu]

@StormLiangMS this PR is ready to be merged, would you please help?

[vaibhavhd]

The version on 202211 and 202205 is same, this needs to be corrected. Blocking merge of this change until that.

[vadymhlushko-mlnx]

The version on 202211 and 202205 is same, this needs to be corrected. Blocking merge of this change until that.

I've added a placeholder for the version_3_0_7 which is the same as for the 202205 branch. Could you please tell me if it is correct, if no could you please explain the logic behind defining proper DB migration version per branch?

[vadymhlushko-mlnx]

The version on 202211 and 202205 is same, this needs to be corrected. Blocking merge of this change until that.

I've added a placeholder for the version_3_0_7 which is the same as for the 202205 branch. Could you please tell me if it is correct, if no could you please explain the logic behind defining proper DB migration version per branch?

@vaibhavhd kind reminder