Fix DB indices for phys_locations and topology

[shamrickus]

What does this PR (Pull Request) do?

• This PR fixes TODB: Incorrect or missing indexes #6066.

Which Traffic Control components are affected by this PR?

• Traffic Ops

What is the best way to verify this PR?

Run the db/admin tool with migrations. Verify the indices are correct. Verify the rollback works correctly.

If this is a bug fix, what versions of Traffic Control are affected?

• master
• 5.1.2

The following criteria are ALL met by this PR

• This PR includes tests OR I have explained why tests are unnecessary
• This PR includes documentation OR I have explained why documentation is unnecessary
• This PR includes an update to CHANGELOG.md OR such an update is not necessary
• This PR includes any and all required license headers
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)

[zrhoffman]

,> IF EXISTS/IF NOT EXISTS

I don't think migrations should succeed error-free if the pre-migration state is not what is expected. The migration version we keep track of should indicate whether these indices already exist and what their names are.

Because the migration version is increased on success, the migration won't rerun anyway, so we shouldn't need the IF EXISTS. If the migration does not do anything, or if it fails, that is potentially useful information that we don't want to hide.

[zrhoffman]

• Verified that indices are fixed after applying 2021080408053529_fix_indices.up.sql
• Verified that a DB dump after applying 2021080408053529_fix_indices.up.sql and 2021080408053529_fix_indices.down.sql is identical to a DB dump after running all migrations on the Apache master branch