[202111][db_migrator] Add migration of FLEX_COUNTER_DELAY_STATUS during 1911->2111 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 -> 202111.

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)

[liat-grozovik]

@vadymhlushko-mlnx pls check failures

[vadymhlushko-mlnx]

@vadymhlushko-mlnx pls check failures

the 202111 branch CI is currently broken.
We are waiting sonic-utilities/pull/2880 to be merged

[vaibhavhd]

I just noticed that 202012 and 202111 are creating same versions w/ different migration logic.

I think the deviation begun starting version_2_0_0. This is not expected as now same DB version will have different looking config (or other db) schema.

This almost sounds like an issue that was earlier seen for 202211 branch: https://github.com/sonic-net/sonic-utilities/pull/2470/files

Unfortuantely, like before, we did not lock new version for 202111 branch. This is not an issue just w/ this PR, rather this is a missed step in new branch creation.

I think we need to lock a version everytime a feature branch is created. This needs further discussion and agreement w/ branch owners.

[vadymhlushko-mlnx]

I just noticed that 202012 and 202111 are creating same versions w/ different migration logic.

I think the deviation begun starting version_2_0_0. This is not expected as now same DB version will have different looking config (or other db) schema.

This almost sounds like an issue that was earlier seen for 202211 branch: https://github.com/sonic-net/sonic-utilities/pull/2470/files

Unfortuantely, like before, we did not lock new version for 202111 branch. This is not an issue just w/ this PR, rather this is a missed step in new branch creation.

I think we need to lock a version everytime a feature branch is created. This needs further discussion and agreement w/ branch owners.

Could you please tell me with whom I could talk about this versioning issue?

[vadymhlushko-mlnx]

I just noticed that 202012 and 202111 are creating same versions w/ different migration logic.
I think the deviation begun starting version_2_0_0. This is not expected as now same DB version will have different looking config (or other db) schema.
This almost sounds like an issue that was earlier seen for 202211 branch: https://github.com/sonic-net/sonic-utilities/pull/2470/files
Unfortuantely, like before, we did not lock new version for 202111 branch. This is not an issue just w/ this PR, rather this is a missed step in new branch creation.
I think we need to lock a version everytime a feature branch is created. This needs further discussion and agreement w/ branch owners.

Could you please tell me with whom I could talk about this versioning issue?

@vaibhavhd kind reminder