MONGOCRYPT-770 do not warn if local schema does not require encryption

[kevinAlbs]

Summary

Do not warn if local schema does not require encryption

Verified by this patch build: https://spruce.mongodb.com/version/679f718a7f3b450007729cee

Background & Motivation

libmongocrypt currently logs a warning if a response from query analysis (mongocryptd/crypt_shared) indicates a local schema does not require encryption. However, this log is generated even for an empty local schema. I do not expect configuring an empty local schema to be discouraged. Quoting the spec:

Drivers MUST document that a local schema is more secure

I expect this warning was intended to inform users that non-encryption JSON schema validation does not apply. However, mongocryptd already errors if a local schema is sent with JSON schema keywords that do not apply. Example:

client = MongoClient(auto_encryption_opts=opts)
client.drop_database("db")
client["db"]["coll"].insert_one({}) # Exception: JSON schema keyword 'required' is only allowed with a remote schema

Query analysis 8.1 supports a new field csfleEncryptionSchemas to accept multiple JSON Schemas. The replied schemaRequiresEncryption only indiciates if any of the sent schemas require encryption. Multiple schemas further complicates this warning check (E.g. should libmongocrypt warn if "schemaRequiresEncryption": false and all schemas are local and non-empty?).

Since the warning seems flawed and redundant with checks done in query analysis, this PR proposes removing.

[rcsanchez97]

LGTM