Remove testmode option, enable it unconditionally

[kssenii]

Changelog category (leave one):

• Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):
Remove testmode option, enable it unconditionally

[kssenii]

@Mergifyio update

[mergify]

update

✅ Branch has been successfully updated

[alexey-milovidov]

@KochetovNicolai let's continue.

[KochetovNicolai]

It's ok to me, there are still a few test which fail for reason

[kssenii]

Stateless tests (release, DatabaseReplicated, actions) [1/2] — fail: 1

-- 01165_lost_part_empty_partition (DB::Exception: Received from localhost:9000. DB::Exception: Existing table metadata in ZooKeeper differs in partition key expression. Stored in ZooKeeper (query: create table rmt1 (n UInt8, m Int32, d Date, t DateTime) engine=ReplicatedMergeTree('/test/01165/{database}/rmt', '1') order by n partition by (n, m, d, t);)) -- not related as even no test hints in this query

Stateless tests (aarch64, actions) — fail: 3

-- failed tests also do not even contain test hints - not related