release-22.2: roachtest: display diff when failing system upgrade test

[ajwerner]

Backport 1/1 commits from #93610.

/cc @cockroachdb/release

---

Before this change, the test would not show diffs like this:

Diff:
@@ -29,11 +29,11 @@
 	"lastUpdated" TIMESTAMP NOT NULL DEFAULT now():::TIMESTAMP,
 	"valueType" STRING NULL,
 	CONSTRAINT "primary" PRIMARY KEY (name ASC),
 	FAMILY "fam_0_name_value_lastUpdated_valueType" (name, value, "lastUpdated", "valueType")
 );
-CREATE SEQUENCE public.descriptor_id_seq MINVALUE 1 MAXVALUE 9223372036854775807 INCREMENT 1 START 1;
+CREATE SEQUENCE public.descriptor_id_seq MINVALUE 1 MAXVALUE 9223372036854775807 INCREMENT 1 START 104;
 CREATE TABLE public.tenants (
 	id INT8 NOT NULL,
 	active BOOL NOT NULL DEFAULT true,
 	info BYTES NULL,
 	name STRING NULL AS (crdb_internal.pb_to_json('cockroach.sql.sqlbase.TenantInfo':::STRING, info)->>'name':::STRING) VIRTUAL,
----

release justification: testing only change

Epic: None

Relates to debugging #95503

Release note: None

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues or test-only changes.
• Patches should not break backwards-compatibility.
• Patches should change as little code as possible.
• Patches should not change on-disk formats or node communication protocols.
• Patches should not add new functionality.
• Patches must not add, edit, or otherwise modify cluster versions; or add version gates.

If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters.
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

• What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
• Will this work in a cluster of mixed patch versions? Did we test that?
• If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

[cockroach-teamcity]

This change is 

[ajwerner]

TFTR!