Fix regression of renderer

[lunny]

Unfortunately, #15175 missed a feature that csv or external renderer could ignore PostProcess to make the render speed up which introduced at #15153. This PR will fix that.

This PR also fixed another bug which external renderers will load twice when settings reload. From https://discord.com/channels/322538954119184384/323701541297192961/851123308321046538 thanks @KN4CK3R

[codecov-commenter]

Codecov Report

Merging #16091 (24f049d) into main (ee5e1c4) will increase coverage by 0.11%.
The diff coverage is 70.00%.

❗ Current head 24f049d differs from pull request most recent head 99197e2. Consider uploading reports for the commit 99197e2 to get more accurate results

@@            Coverage Diff             @@
##             main   #16091      +/-   ##
==========================================
+ Coverage   44.06%   44.18%   +0.11%     
==========================================
  Files         683      683              
  Lines       82358    82367       +9     
==========================================
+ Hits        36295    36396     +101     
+ Misses      40176    40071     -105     
- Partials     5887     5900      +13     

Impacted Files	Coverage Δ
modules/markup/renderer.go	67.00% <70.00%> (-5.53%)	⬇️
modules/git/repo_base_nogogit.go	82.85% <0.00%> (-2.86%)	⬇️
modules/git/utils.go	62.50% <0.00%> (-2.78%)	⬇️
models/error.go	39.84% <0.00%> (+0.31%)	⬆️
services/pull/pull.go	43.37% <0.00%> (+0.45%)	⬆️
routers/api/v1/repo/pull.go	28.74% <0.00%> (+0.59%)	⬆️
modules/markup/markdown/markdown.go	63.43% <0.00%> (+0.74%)	⬆️
models/notification.go	66.07% <0.00%> (+0.88%)	⬆️
modules/queue/unique_queue_disk_channel.go	48.63% <0.00%> (+1.36%)	⬆️
modules/process/manager.go	75.30% <0.00%> (+2.46%)	⬆️
... and 8 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b3ef6a6...99197e2. Read the comment docs.