fix: inconsistent timezone handling in daily allocation aggregation

[amandavialva01]

Ticket

CM-440

Description

Our Historical Usage page fetches allocations by date in UTC time specifically, and we store allocations without a timezone, which converts the input time to UTC before storing the timestamp without the timezone internally.

However, fetching timestamps with no timezone and then casting to timestamptz (with a timezone) only adds a timezone to the stored time stamp, doing no internal conversion from UTC to the corresponding time in the user's set timezone. (so ('2024-10-02 01:30'::timestamp)::timestamptz = 2024-10-02 01:30 <user_set_timezone>, which isn't what we want.

With the changes in this PR, we keep consistent with how allocations are stored and continue to handle them in the resource_aggregates table without casting to a timestamptz.

Test Plan

CI passes (automated testing).

Checklist

• Changes have been manually QA'd
• New features have been approved by the corresponding PM
• User-facing API changes have the "User-facing API Change" label
• Release notes have been added as a separate file under docs/release-notes/
  See Release Note for details.
• Licenses have been included for new code which was copied and/or modified from any external code

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.72%. Comparing base (3a91552) to head (ee4d92c).
Report is 29 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9888      +/-   ##
==========================================
+ Coverage   54.71%   54.72%   +0.01%     
==========================================
  Files        1261     1261              
  Lines      155984   155984              
  Branches     3589     3590       +1     
==========================================
+ Hits        85348    85365      +17     
+ Misses      70504    70487      -17     
  Partials      132      132              

Flag	Coverage Δ
backend	45.20% <100.00%> (+0.03%)	⬆️
harness	72.60% <ø> (ø)
web	54.47% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
master/internal/db/postgres_cluster.go	50.54% <100.00%> (+32.96%)	⬆️

... and 6 files with indirect coverage changes

[netlify]

✅ Deploy Preview for determined-ui canceled.

Name	Link
🔨 Latest commit	ee4d92c
🔍 Latest deploy log	https://app.netlify.com/sites/determined-ui/deploys/66d73cc985845c00082e4378

[kkunapuli]

LGTM