Revert "Golang 1.18 (#3508)"

[seemiller]

This reverts commit b6bc162.

What this PR does / why we need it

Too many Bolt build failures. Need to update downstream dependencies/components first.

Which issue(s) this PR fixes

Fixes #

Describe testing done for PR

Release note

Additional information

Special notes for your reviewer

[github-actions]

Cluster Generation A/B Results:
https://storage.googleapis.com/tkg-clustergen/3571/20221006194013/clustergen.diff.txt
Author/reviewers:
Please review to verify that the effects on the generated cluster configurations are exactly what the PR intended, and give a thumbs-up if so.

[imikushin]

LGTM

[codecov]

Codecov Report

Merging #3571 (a30806e) into main (59f44fd) will decrease coverage by 0.84%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3571      +/-   ##
==========================================
- Coverage   47.19%   46.34%   -0.85%     
==========================================
  Files         423      448      +25     
  Lines       42307    43871    +1564     
==========================================
+ Hits        19966    20334     +368     
- Misses      20579    21761    +1182     
- Partials     1762     1776      +14     

Impacted Files	Coverage Δ
cmd/cli/plugin/tkr/v1alpha3/os.go	73.50% <0.00%> (-0.86%)	⬇️
...cluster/delete_machinehealthcheck_control_plane.go	16.66% <0.00%> (ø)
cmd/cli/plugin/cluster/get.go	6.27% <0.00%> (ø)
cmd/cli/plugin/cluster/create.go	41.30% <0.00%> (ø)
cmd/cli/plugin/cluster/main.go	0.00% <0.00%> (ø)
cmd/cli/plugin/cluster/set_node_pool.go	14.63% <0.00%> (ø)
cmd/cli/plugin/cluster/machinehealthcheck.go	100.00% <0.00%> (ø)
.../cli/plugin/cluster/get_machinehealthcheck_node.go	9.30% <0.00%> (ø)
.../cli/plugin/cluster/set_machinehealthcheck_node.go	23.33% <0.00%> (ø)
cmd/cli/plugin/cluster/upgrade.go	57.55% <0.00%> (ø)
... and 19 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.