[draft] sr: Perform raw schema lookup first

[michael-redpanda]

Certain SR clients perform the following pattern to lookup schema IDs:

* POST /subject/sub/versions?normalize=true -d {schema}
* GET /subject/sub/versions/latest -> this returns the schema and latest version but NOT IDs
* POST /subject/sub -d {schema-from-get} -> this returns ID

In our SR, a call to POST /subject/sub without normalize=true will result in this schema being sanitized which may change the content of the schema. The change introduced in this PR is to perform a direct lookup of the raw provided schema before we either normalize or sanitize it.

Backports Required

• none - not a bug fix
• none - this is a backport
• none - issue does not exist in previous branches
• none - papercut/not impactful enough to backport
• v24.3.x
• v24.2.x
• v24.1.x

Release Notes

• None

[vbotbuildovich]

CI test results

test results on build#61637

test_id	test_kind	job_url	test_status	passed
rptest.tests.compaction_recovery_test.CompactionRecoveryTest.test_index_recovery	ducktape	https://buildkite.com/redpanda/redpanda/builds/61637#0194d876-4604-43ff-a56e-08574e17974e	FLAKY	1/2
rptest.tests.compaction_recovery_test.CompactionRecoveryTest.test_index_recovery	ducktape	https://buildkite.com/redpanda/redpanda/builds/61637#0194d89b-d1b5-48da-b913-dc9fabd8f546	FLAKY	1/2
rptest.tests.compaction_recovery_test.CompactionRecoveryUpgradeTest.test_index_recovery_after_upgrade	ducktape	https://buildkite.com/redpanda/redpanda/builds/61637#0194d876-4605-463f-80cf-5c0077eb05a7	FLAKY	1/2
rptest.tests.datalake.compaction_test.CompactionGapsTest.test_translation_no_gaps.cloud_storage_type=CloudStorageType.S3.catalog_type=CatalogType.REST_JDBC	ducktape	https://buildkite.com/redpanda/redpanda/builds/61637#0194d89b-d1b3-434c-a1d6-1f259703559f	FLAKY	1/2
rptest.tests.datalake.datalake_e2e_test.DatalakeE2ETests.test_topic_lifecycle.cloud_storage_type=CloudStorageType.S3.catalog_type=CatalogType.REST_HADOOP	ducktape	https://buildkite.com/redpanda/redpanda/builds/61637#0194d876-4604-43ff-a56e-08574e17974e	FLAKY	1/2
rptest.tests.topic_delete_test.TopicDeleteCloudStorageTest.drop_lifecycle_marker_test.cloud_storage_type=CloudStorageType.S3	ducktape	https://buildkite.com/redpanda/redpanda/builds/61637#0194d876-4605-463f-80cf-5c0077eb05a7	FLAKY	1/2