helm: Enable cephfs volume expansion by default

[travisn]

Description of your changes:
The cluster helm chart missed adding the default setting for the volume expansion, so now we enable it by default.

Which issue is resolved by this Pull Request:
Resolves #9120

Checklist:

• Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide.
• Skip Tests for Docs: Add the flag for skipping the build if this is only a documentation change. See here for the flag.
• Skip Unrelated Tests: Add a flag to run tests for a specific storage provider. See test options.
• Reviewed the developer guide on Submitting a Pull Request
• Documentation has been updated, if necessary.
• Unit tests have been added, if necessary.
• Integration tests have been added, if necessary.
• Pending release notes updated with breaking and/or notable changes, if necessary.
• Upgrade from previous release is tested and upgrade user guide is updated, if necessary.
• Code generation (make codegen) has been run to update object specifications, if necessary.

[Rakshith-R]

The allowVolumeExpansion: line in cephblocksystem also needs to be added to cephfilesystem.yaml

rook/cluster/charts/rook-ceph-cluster/templates/cephblockpool.yaml

Lines 23 to 26 in 0a3945d

	reclaimPolicy: {{ default "Delete" $blockpool.storageClass.reclaimPolicy }}
	allowVolumeExpansion: {{ default "true" $blockpool.storageClass.allowVolumeExpansion }}
	{{ end }}
	{{ end }}

rook/cluster/charts/rook-ceph-cluster/templates/cephfilesystem.yaml

Lines 24 to 26 in 0a3945d

	reclaimPolicy: {{ default "Delete" $filesystem.storageClass.reclaimPolicy }}
	{{ end }}
	{{ end }}

[Rakshith-R]

LGTM, thanks!