[bug] fix http template dict empty error

[benja-wu]

Problem

1. HTTPTemplate doesn't work as expected in HTTPPipeline

Details

• As the former design, HTTPTempalte will save one filter's request, and the response modified by it into context's template dictionary if necessary(If it can find the template in filter's spec), the flow is a sequence. That means the flow will look like

1. save http request to be handle by filter1
2. fitler1 handle
3. save http response modified by filter1
4. save http request to be handle by filter2
5. filter2 handle
6. save http response modified by filter2
....

• After we introduced responsibility chain into HTTPPipline, the flow logic had been changed from sequence to stack. That means the flow looks like

1. save http request to be handle by filter1
2. filter1 handle
3. save http request to be handle by filter2
4. filter2 handle
5. save http response modified by filter2
6. save http response modified by filter1
....

• This bug fixing is aiming to correct the HTTPTemplate saving flow back to the sequence type.

[megaeasex]

[TASK:easegress-pr-test SUCCESS]megaease/easegress Pull Request 163 Deploy Test Success

[codecov-commenter]

Codecov Report

Merging #163 (0c28551) into main (c32e42c) will increase coverage by 0.16%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #163      +/-   ##
==========================================
+ Coverage   57.81%   57.98%   +0.16%     
==========================================
  Files          38       38              
  Lines        3658     3658              
==========================================
+ Hits         2115     2121       +6     
+ Misses       1437     1433       -4     
+ Partials      106      104       -2     

Impacted Files	Coverage Δ
pkg/util/jmxtool/common.go	72.97% <0.00%> (+4.05%)	⬆️
pkg/util/jmxtool/agent_controller.go	54.09% <0.00%> (+4.91%)	⬆️

---

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 c32e42c...0c28551. Read the comment docs.

[localvar]

line 492-495 should be removed.

[benja-wu]

line 492-495 should be removed.

My bad, let me update it

[megaeasex]

[TASK:easegress-pr-test SUCCESS]megaease/easegress Pull Request 163 Deploy Test Success

[megaeasex]

[TASK:easegress-pr-test SUCCESS]megaease/easegress Pull Request 163 Deploy Test Success

[megaeasex]

[TASK:easegress-pr-test SUCCESS]megaease/easegress Pull Request 163 Deploy Test Success