fix: Slice on unevaluated QuerySet for Organization.has_single_owner

[dashed]

Found this while fixing tests for split silos.

This was a regression from 131596d, and the implementation of def has_single_owner had this optimization prior to the refactor: https://github.com/getsentry/sentry/blame/1acfc6443fa031fb932115c69ddbe12c01bd8b8e/src/sentry/models/organization.py#L310-L316

Slicing on unevaluated QuerySet would add the appropriate LIMIT keywords on the generated SQL query:

• https://docs.djangoproject.com/en/4.2/ref/models/querysets/
• https://docs.djangoproject.com/en/4.2/topics/db/queries/#limiting-querysets

[dashed]

Here, owners should return at most 2 records.

[cathteng]

thanks for catching this!

[codecov]

Codecov Report

Merging #55715 (964e010) into master (ea14f74) will decrease coverage by 0.01%.
Report is 16 commits behind head on master.
The diff coverage is 85.00%.

@@            Coverage Diff             @@
##           master   #55715      +/-   ##
==========================================
- Coverage   80.13%   80.12%   -0.01%     
==========================================
  Files        5049     5051       +2     
  Lines      216398   216505     +107     
  Branches    36617    36647      +30     
==========================================
+ Hits       173412   173481      +69     
- Misses      37682    37706      +24     
- Partials     5304     5318      +14     

Files Changed	Coverage
...app/components/profiling/flamegraph/flamegraph.tsx	ø
static/app/utils/profiling/units/units.ts	ø
static/app/utils/replays/replayReader.tsx	ø
static/app/views/monitors/details.tsx	ø
.../performance/landing/views/allTransactionsView.tsx	ø
...pp/views/performance/landing/views/backendView.tsx	ø
...e/landing/widgets/components/performanceWidget.tsx	ø
...ance/landing/widgets/components/widgetChartRow.tsx	ø
...rmance/landing/widgets/components/widgetHeader.tsx	ø
...ing/widgets/transforms/transformTrendsDiscover.tsx	ø
... and 13 more