Ensure that refreshed creds are used to update remote.

[nishkrishnan]

Fixes: #1236

Basically just ensures we are always using the latest credential URL in the case that we already have our repo cloned at the right commit and we want to check if master has diverged.

Additionally, also ensures we can still write creds even when our creds are nuked.

[codecov]

Codecov Report

Merging #1238 into master will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1238      +/-   ##
==========================================
+ Coverage   69.93%   70.00%   +0.06%     
==========================================
  Files          71       71              
  Lines        5359     5368       +9     
==========================================
+ Hits         3748     3758      +10     
+ Misses       1263     1262       -1     
  Partials      348      348              

Impacted Files	Coverage Δ
server/events/git_cred_writer.go	78.94% <100.00%> (+1.16%)	⬆️
server/events/working_dir.go	77.77% <100.00%> (+2.50%)	⬆️

---

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 3ab63bc...1110c52. Read the comment docs.