URLRewrite filter on empty match prefix

[sadovnikov]

What type of PR is this?

Adding a test to demonstrate a bug with the URLRewrite filter.
Not to be merged until #5256 is resolved.

Which issue(s) this PR fixes:

Instead of "/prefix-match/doc", the resulting request will be "/prefix-matchdoc"

Found in end-to-end test logs

not ready yet: expected path to be /prefix-match/doc, got /prefix-matchdoc (after 1.513µs)

Release Notes: No

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.88%. Comparing base (c492089) to head (b52de06).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5254      +/-   ##
==========================================
- Coverage   66.94%   66.88%   -0.07%     
==========================================
  Files         210      210              
  Lines       33034    33034              
==========================================
- Hits        22116    22096      -20     
- Misses       9581     9596      +15     
- Partials     1337     1342       +5     

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[zirain]

e2e failed as expected, @sadovnikov plan to send a fix?

[sadovnikov]

e2e failed as expected, @sadovnikov plan to send a fix?

@zirain, based on the comments in #5256, the fix is not trivial. I hope it will be provided by someone more familiar with the EG code. I'm happy to add more tests but using end-2-end for this seems "too late". Are there unit tests?