Use agent as name where it fits

[honnix]

TL;DR

Use agent as name where it fits

Type

• Bug Fix
• Feature
• Plugin

Are all requirements met?

• Code completed
• Smoke tested
• Unit tests added
• Code documentation added
• Any pending items have an associated Issue

Complete description

This is some leftover of #368 where we should have aligned the naming better. Note that this PR has no breaking change.

Tracking Issue

flyteorg/flyte#3823

Follow-up issue

NA

[codecov]

Codecov Report

Merging #381 (f95d6fc) into master (22d2635) will increase coverage by 1.34%.
The diff coverage is 73.33%.

❗ Current head f95d6fc differs from pull request most recent head 6a87399. Consider uploading reports for the commit 6a87399 to get more accurate results

@@            Coverage Diff             @@
##           master     #381      +/-   ##
==========================================
+ Coverage   63.01%   64.36%   +1.34%     
==========================================
  Files         154      154              
  Lines       13071    10605    -2466     
==========================================
- Hits         8237     6826    -1411     
+ Misses       4218     3163    -1055     
  Partials      616      616              

Flag	Coverage Δ
unittests	?

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Files Changed	Coverage Δ
go/tasks/plugins/webapi/agent/plugin.go	71.14% <73.33%> (+3.00%)	⬆️

... and 134 files with indirect coverage changes

[honnix]

@pingsutw Wanna merge this?