fix: ensure all updates are processed in xds ir update test

[dboslee]

What this PR does / why we need it:
TestXdsIRUpdates added in #1795 is flaky. This adds a sleep to reduce the chance of failing. Open to suggestions to avoid the sleep but this pattern is also used in another test here

gateway/internal/message/watchutil_test.go

Line 43 in 080674a

time.Sleep(100 * time.Millisecond)

[arkodg]

how about using require.Eventually e.g. in here ?

[arkodg]

would be good to test this with go test ./... -count=20

[codecov]

Codecov Report

Merging #1799 (50024ee) into main (8398049) will increase coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1799      +/-   ##
==========================================
+ Coverage   65.04%   65.12%   +0.08%     
==========================================
  Files          84       84              
  Lines       12230    12230              
==========================================
+ Hits         7955     7965      +10     
+ Misses       3764     3756       -8     
+ Partials      511      509       -2     

see 2 files with indirect coverage changes

[dboslee]

how about using require.Eventually e.g. in here ?

@arkodg updated in 5fcae5d

require.Eventually didn't exactly fit here. Checking that the number of updates is eventually equal to the desired value could work but could also give a false positive where the number of updates would have been incremented past the desired value otherwise.

This updated version of the test uses the start and end keys to indicate the first and last updates so we know when to close the map and ensure that all events have been processed.

I ran go test -timeout 10s -run ^TestXdsIRUpdates$ github.com/envoyproxy/gateway/internal/message -count 1000 successfully.

[arkodg]

LGTM thanks !