Ignore zshippable in minor version during upgrade

[adduarte]

During dev testing of cluster upgrade functionality, some of the package versions will have the postfix "-zshippable".

The libraries used to compare versions of packages during upgrade look at a version string like "0.12.1+vmware.2-tkg.2-zshippable", and assume the minor version, "2-zshippable", is a non-number.

The libraries also look at a version string like "0.12.1+vmware.2-tkg.3", and assume the minor version "3" is a number.

The problem comes about because the same libraries see a non-number minor version as newer than any number version.
So the version 0.12.1+vmware.2-tkg.2-zshippable is newer than 0.12.1+vmware.2-tkg.3, which is incorrect

To allow for dev testing to proceed we remove the "-zshippable" postfix right before the version strings are compared.

What this PR does / why we need it

Which issue(s) this PR fixes

Fixes #4379

Describe testing done for PR

Unit test added

Release note

the postfix "-zshippable" is ignore when comparing package versions during upgrade.

Additional information

Special notes for your reviewer

[codecov]

Codecov Report

Merging #4378 (c8c4d34) into main (0c0f23e) will decrease coverage by 0.91%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #4378      +/-   ##
==========================================
- Coverage   49.52%   48.61%   -0.91%     
==========================================
  Files         452      482      +30     
  Lines       44986    47108    +2122     
==========================================
+ Hits        22278    22901     +623     
- Misses      20584    22031    +1447     
- Partials     2124     2176      +52     

Impacted Files	Coverage Δ
addons/webhooks/clusterbootstrap_webhook.go	45.47% <100.00%> (+0.29%)	⬆️
addons/controllers/addon_controller.go	63.40% <0.00%> (-2.07%)	⬇️
...ons/controllers/packageinstallstatus_controller.go	77.99% <0.00%> (-1.16%)	⬇️
addons/controllers/clusterbootstrap_controller.go	64.50% <0.00%> (-0.09%)	⬇️
cmd/cli/plugin/cluster/delete_node_pool.go	16.66% <0.00%> (ø)
cmd/cli/plugin/cluster/get.go	6.27% <0.00%> (ø)
.../isolated-cluster/imgpkginterface/client_imgpkg.go	0.00% <0.00%> (ø)
cmd/cli/plugin/cluster/delete.go	12.50% <0.00%> (ø)
.../cli/plugin/cluster/get_machinehealthcheck_node.go	9.30% <0.00%> (ø)
cmd/cli/plugin/isolated-cluster/main.go	0.00% <0.00%> (ø)
... and 27 more

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