Revendor cortex

[owen-d]

This is split into a vendor bump commit and a compatibility commit. Notably we remove a replace directive inherited from cortex which appears no longer necessary:

replace github.com/Azure/go-autorest => github.com/Azure/go-autorest v13.3.0+incompatible

Also this bumps cortex & prometheus, which should enable #2392

[codecov-commenter]

Codecov Report

Merging #2427 into master will increase coverage by 0.13%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #2427      +/-   ##
==========================================
+ Coverage   61.55%   61.69%   +0.13%     
==========================================
  Files         160      160              
  Lines       13612    13611       -1     
==========================================
+ Hits         8379     8397      +18     
+ Misses       4607     4588      -19     
  Partials      626      626              

Impacted Files	Coverage Δ
pkg/loki/modules.go	10.77% <0.00%> (-0.10%)	⬇️
pkg/loki/runtime_config.go	0.00% <0.00%> (ø)
pkg/storage/store.go	62.50% <0.00%> (ø)
pkg/querier/queryrange/downstreamer.go	95.87% <0.00%> (-2.07%)	⬇️
pkg/promtail/targets/file/filetarget.go	69.64% <0.00%> (+1.78%)	⬆️
pkg/promtail/targets/file/tailer.go	76.13% <0.00%> (+2.27%)	⬆️
pkg/promtail/positions/positions.go	59.64% <0.00%> (+13.15%)	⬆️

[cyriltovena]

Lgtm