VAULT-13061: Fix mount path discrepancy in activity log

[miagilepner]

There are two problems this PR fixes:

1. processClientRecord creates maps that key by mount accessor, but we later assume that the key is a mount path in transformActivityLogMounts
2. Sometimes a deleted/empty mount record is thrown out (precomputedQueryWorker), while other times we keep it (transformMonthBreakdowns ). This change means that we will always keep the mount record.

Closes #18814, #18812

[miagilepner]

I want to verify that this is the correct behavior - it seems wrong to me that these currently get thrown out, but I definitely might be missing something

[miagilepner]

and to clarify, deleted mounts were being excluded from the per-mount breakdown of counts. They were still present in the top-level totals.

[mpalmi]

Code looks great! Just a few nits on the tests, mainly relating to clarity. Thanks for including the test with this.

Worth noting: I tested this against your feature branch with the transformMonthBreakdowns changes reset and the test you have passes. Does this align with your expectations, or should we iron out that piece of testing a bit more?

[miagilepner]

Worth noting: I tested this against your feature branch with the transformMonthBreakdowns changes reset and the test you have passes. Does this align with your expectations, or should we iron out that piece of testing a bit more?

The relevant function to revert is transformActivityLogMounts. The test will fail when that function is reverted to what's on origin/main. The additional test comments should also hopefully make clearer what's going on here.