internal/transport: Remove redundant if conditional in http2_server

[chengfang]

In internal/transport/http2_server.go, around line 640, the if-else branches contain the identical code, and should be combined:

if err == io.EOF || err == io.ErrUnexpectedEOF {
  t.Close(err)
  return
}
t.Close(err)
return

RELEASE NOTES: none

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: chengfang / name: Cheng Fang (b8b6bfb)

[codecov]

Codecov Report

Merging #6946 (b8b6bfb) into master (5051eea) will decrease coverage by 0.21%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6946      +/-   ##
==========================================
- Coverage   83.81%   83.61%   -0.21%     
==========================================
  Files         287      287              
  Lines       30930    30926       -4     
==========================================
- Hits        25925    25858      -67     
- Misses       3952     3999      +47     
- Partials     1053     1069      +16     

Files	Coverage Δ
internal/transport/http2_server.go	89.56% <ø> (-0.04%)	⬇️

... and 21 files with indirect coverage changes

[arvindbr8]

LGTM. @zasweq -- do you mind taking a second pass at this?