Make Schema Tracking case-sensitive

[GuptaManan100]

Description

This PR fixes the issue #14671. This fix only works with #14930, so we can't backport this without backporting that PR as well.

Since the planner and all the other components of Vitess treat table names as case-sensitive, so should schema-tracking. This PR makes this change. Surprisingly the only change that was required was in the schema of the internal tables that we create. The tables and views tables for the schema engine where using the varchar columns (with the default collation) to store the table names, causing MySQL to error out with a duplicate key error, when trying to store the information of 2 tables such that their names only differ in casing.
The columns in question have had their collations changed toutfmb3_bin, which is a case-sensitive collation resolving the issue.

Moreover, while I was working on the schema-tracker, I have added more tests, and cleaned up the artificats left from the old way of schema-tracking which can now be removed.

Related Issue(s)

• Fixes Case-sensitive Schema Tracking #14671

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[harshit-gangal]

I think we should port it to v18 as well.

[dbussink]

I think we should port it to v18 as well.

Does this mean we need to separate out the cleanup from the fix here?

[GuptaManan100]

Does this mean we need to separate out the cleanup from the fix here?

No, I'll just resolve the conflicts in the backports. I don't want to create a separate PR unnecessarily.

[frouioui]

Nice catch and nice fix @GuptaManan100!

[GuptaManan100]

This fix only works with #14930, so we can't backport this without backporting that PR as well.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (eddb39e) 47.29% compared to head (9ca2956) 47.29%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14904      +/-   ##
==========================================
- Coverage   47.29%   47.29%   -0.01%     
==========================================
  Files        1137     1137              
  Lines      238684   238647      -37     
==========================================
- Hits       112895   112864      -31     
- Misses     117168   117169       +1     
+ Partials     8621     8614       -7     

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[deepthi]

Why did we choose utf8mb3 and utf8mb3_bin versus utf8mb4 and utf8mb4_bin? I ask because utf8mb3 has been deprecated.

You should also be aware that the utf8mb3 character set is deprecated and you should expect it to be removed in a future MySQL release. Please use utf8mb4 instead.

https://dev.mysql.com/doc/refman/8.0/en/charset-unicode-utf8mb3.html

[dbussink]

See my comment in #14904 (comment)

I deliberately suggested utf8mb3 since that still is used for internal system tables for MySQL, even though it’s deprecated.