add retry in func UpdateEgressGateway

[bzsuni]

fix resourceVersion modified when update EgressGateway #661

[codecov]

Codecov Report

Merging #662 (58ae14a) into main (3324215) will not change coverage.
Report is 1 commits behind head on main.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #662   +/-   ##
=======================================
  Coverage   10.45%   10.45%           
=======================================
  Files          19       19           
  Lines        3864     3864           
=======================================
  Hits          404      404           
  Misses       3384     3384           
  Partials       76       76           

Flag	Coverage Δ
unittests	10.45% <ø> (ø)

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[weizhoublue]

有这么多用例在并发操作 egressGateway
这个 update 只是简单的 尝试 3 此，我看 并发的用例也不只 3 个，失败起来，3 次重试都不够
并且，这个 update 也不区分 是否 resourceviesion 是否 冲突 等 能够容忍的错误，万一有其他错误，岂不 被忽略了

应该要有一个更加聪明的写法，否则还会出现