backport - fix collation failure

[tanjinx]

Description

The CI test Unit Test (mysql80) / test (pull_request) failed with this error:

--- FAIL: TestComparisonSemantics (13.17s)
    --- FAIL: TestComparisonSemantics/equals (6.40s)
        coercion_test.go:202: expected dec8_swedish_ci vs utf8_general_ci to fail coercion: Illegal mix of collations (dec8_swedish_ci,EXPLICIT) and (utf8mb3_general_ci,EXPLICIT) for operation '=' (errno 1267) (sqlstate HY000) during query: SELECT CAST(((_dec8 X'6162636441424344[30](https://github.com/slackhq/vitess/actions/runs/3414744449/jobs/5683094619#step:8:31)31323334' COLLATE "dec8_swedish_ci") = (_utf8 X'61626364414243443031323334' COLLATE "utf8_general_ci")) AS BINARY), COLLATION((_dec8 X'61626364414243443031323334' COLLATE "dec8_swedish_ci") = (_utf8 X'61626364414243443031323334' COLLATE "utf8_general_ci")), COERCIBILITY((_dec8 X'61626364414243443031323334' COLLATE "dec8_swedish_ci") = (_utf8 X'61626364414243443031323334' COLLATE "utf8_general_ci"))

the upstream fixed through 2 PRs:

• Skip TestComparisonSemantics test vitessio/vitess#11474
• collations: fix coercion semantics according to 8.0.31 changes vitessio/vitess#11487
  but v13 does not have the api used by collations: fix coercion semantics according to 8.0.31 changes vitessio/vitess#11487, so backporting 11474 only which should fix the error.

Related Issue(s)

Checklist

• "Backport me!" label has been added if this change should be backported
• Tests were added or are not required
• Documentation was added or is not required

Deployment Notes