修复injector挂载sermant会跟skywalking产生冲突的问题

[provenceee]

【修复issue】 #1258

【修改内容】修改injector注入命令的行为

【用例描述】注入行为分别为before、after、ignore时，是否可以按预期注入命令

【自测情况】before时，在原命令前注入，after时，在原命令后注入，ignore时，不注入

【影响范围】需要更新文档

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.13% ⚠️

Comparison is base (3e4f10e) 41.63% compared to head (fcc9a8d) 41.51%.

Additional details and impacted files

@@             Coverage Diff              @@
##              1.1.x    #1262      +/-   ##
============================================
- Coverage     41.63%   41.51%   -0.13%     
+ Complexity     3219     3212       -7     
============================================
  Files           817      817              
  Lines         18029    18029              
  Branches       1960     1960              
============================================
- Hits           7507     7485      -22     
- Misses         9577     9606      +29     
+ Partials        945      938       -7     

Flag	Coverage Δ
unittests	41.51% <ø> (-0.13%)	⬇️

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see 14 files with indirect coverage changes

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