[release/10.0] Fix parameter deduplication logic bug

[roji]

Fixes #37189

Description

When the same parameter is referenced multiple times, EF performs deduplication to send only a single SQL parameter to the database, reducing transfer size etc. 10.0 Introduced various changes to this mechanism as part of the general parameter logic cleanup (in #35200), and a one-lineer bug slipped in.

Customer impact

This bug can manifest in various ways when the same parameter or referenced multiple times, or multiple parameters are different only in case sensitivity (see, #37096, #36917 (comment)). This can cause queries which previously worked to fail, and in worse edge cases, queries to return incorrect data because of deduplication to the wrong parameter with the wrong store type (data corruption).

How found

Multiple customers reported on 10.0.0

Regression

Yes

Testing

Testing already existed, but asserted incorrectly.

Risk

Very low, one-line trivial change. Quirk added.

[artl93]

Is the old behavior switch switching on the 10.0.0 behavior, or is it putting in the 9.0 behavior… Trying to follow

[roji]

Is the old behavior switch switching on the 10.0.0 behavior, or is it putting in the 9.0 behavior…

The switch switches to the (buggy) 10.0.0 behavior, just in case. 9.0 was quite a different implementation so there's no option to switch to that; but we're not aware of a problem with the general 10.0 implementation - just this one-liner typo bug.