chore: remove unnecessary skip_failed_rules config in slt (apache#18117)

## Which issue does this PR close?

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- Closes apache#3695
- Closes apache#3797

## Rationale for this change

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Was looking at above issues and I don't believe we skip the failed rules
for any tests anymore (default for the config is also `false`), apart
from this cleanup, so filing this PR so we can close the issues. Seems
we only do in this `window.slt` test after this fix:


https://github.com/apache/datafusion/blob/621a24978a7a9c6d2b27973d1853dbc8776a56b5/datafusion/sqllogictest/test_files/window.slt#L2587-L2611

Which seems intentional.

## What changes are included in this PR?

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Remove unnecessary `skip_failed_rules` config.

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Existing tests.

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No.

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Author: Jefffrey

datafusion/sqllogictest/test_files/timestamps.slt

@@ -643,11 +643,7 @@ select date '1994-01-01' - interval '1' day as date;
 ----
 1993-12-31
 
-
 # cast_string_to_time()
-statement ok
-set datafusion.optimizer.skip_failed_rules = false
-
 query DDDD
 select
         time '08:09:10.123456789' as time_nano,
@@ -668,10 +664,6 @@ SELECT TIME '24:01:02' as time;
 query error Arrow error: Parser error: Invalid timezone "ZZ": failed to parse timezone
 SELECT TIMESTAMP '2023-12-05T21:58:10.45ZZ';
 
-statement ok
-set datafusion.optimizer.skip_failed_rules = true
-
-
 # cast_to_timestamp_twice
 query P
 select to_timestamp(a) from (select to_timestamp(1) as a) A;