chore: return generic error for user when validating webhook fails unexpectedly

[jeffreylimnardy]

Description

Changes proposed in this pull request (what was done and why):

• ottl.NewTransformSpecValidator and ottl.NewFilterSpecValidator are not dependent on user input and thus errors returned by these functions must be generic to not confuse user but detailed error messages should be provided as logs for maintainers to identify issues

Changes refer to particular issues, PRs or documents:

Traceability

• The PR is linked to a GitHub issue.
• The follow-up issues (if any) are linked in the Related Issues section.
• If the change is user-facing, the documentation has been adjusted.
• If a CRD is changed, the corresponding Busola ConfigMap has been adjusted.
• The feature is unit-tested.
• The feature is e2e-tested.