e2e: fix some tests

[zirain]

1. prometheus address wrong on IPv6
2. make E2E_TIMEOUT configurable
3. skip EGUpgradeTest on IPv6

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.63%. Comparing base (97a5d68) to head (7899fdd).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4729      +/-   ##
==========================================
+ Coverage   65.58%   65.63%   +0.04%     
==========================================
  Files         211      211              
  Lines       31998    31998              
==========================================
+ Hits        20986    21002      +16     
+ Misses       9768     9758      -10     
+ Partials     1244     1238       -6     

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[zhaohuabing]

LGTM thanks!