Improve notification pager

[lunny]

This PR has two improvements for notification pager.

• When click read button on second/third page, it will stay the same page but not go to first page.
• When click read button on last page and last record, it will go to the new last page but not go to first page.

[codecov-io]

Codecov Report

Merging #9821 into master will decrease coverage by <.01%.
The diff coverage is 18.18%.

@@            Coverage Diff             @@
##           master    #9821      +/-   ##
==========================================
- Coverage   42.23%   42.22%   -0.01%     
==========================================
  Files         603      603              
  Lines       78880    78884       +4     
==========================================
- Hits        33313    33308       -5     
- Misses      41487    41494       +7     
- Partials     4080     4082       +2

Impacted Files	Coverage Δ
routers/user/notification.go	39.81% <18.18%> (-1.54%)	⬇️
services/pull/patch.go	62.89% <0%> (-3.15%)	⬇️
services/pull/merge.go	50.69% <0%> (-0.7%)	⬇️
modules/log/file.go	77.62% <0%> (+2.09%)	⬆️

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[sapk]

Make LGTM work