Make the E2E supporting VKS data mover environment.

[blackpiglet]

• Add new flag DISABLE_VSPHERE_PLUGIN for E2E test.
• Modify the E2E README for the new parameter.
• Add the VolumeSnapshotClass for VKS.
• Modify the plugin install logic.
• Modify the E2E to support data mover cases in VKS.

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• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.93%. Comparing base (db470a7) to head (f9d421e).
Report is 18 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8371      +/-   ##
==========================================
- Coverage   58.95%   58.93%   -0.03%     
==========================================
  Files         367      367              
  Lines       38876    38902      +26     
==========================================
+ Hits        22920    22925       +5     
- Misses      14493    14514      +21     
  Partials     1463     1463              

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[reasonerjt]

Change it to "HasVSpherePlugin"? And following "if" will only need to check this single flag.

[blackpiglet]

I agree that using the positive wording is more intuitive, but we cannot replace all the provider checking with this flag, for example:

						// If the CloudProvider is vSphere and don't need vSphere plugin,
						// Only install the AWS plugin.
						// If do nothing here, the default behavior is
						// installing both AWS and vSphere plugins.
						if OriginVeleroCfg.CloudProvider == Vsphere &&
							OriginVeleroCfg.DisableVspherePlugin {
							OriginVeleroCfg.Plugins = migrationNeedPlugins[AWS][0]
						}

It should be changed to something like the following.
The HasVspherePlugin flag is defaulted to false, so we need to check the provider to make sure it's for vSphere environment.

						// If HasVspherePlugin is false, only install the AWS plugin.
						// If do nothing here, the default behavior is
						// installing both AWS and vSphere plugins.
						if OriginVeleroCfg.CloudProvider == Vsphere &&
							!OriginVeleroCfg.HasVspherePlugin {
							OriginVeleroCfg.Plugins = migrationNeedPlugins[AWS][0]
						}