VAULT-24798: Audit - error tweak

[peteski22]

Don't wrap the underlying error on filter field validation failure.

Once the Operator has seen:

filter references an unsupported field: foo == bar: invalid configuration

... then the following 'extra' info isn't really useful at all:

error finding value in datum: /foo at part 0: couldn't find key: struct field with name "foo"

We document the filter fields for Vault Operators: filter properties for audit devices.

Before:

After:

• Please ignore the sneaky bar in screenshots, which goes against what we document (should be \"bar\")

[github-actions]

CI Results:
All Go tests succeeded! ✅

[github-actions]

Build Results:
All builds succeeded! ✅

[kubawi]

LGTM