[MINOR][DOCS][SQL] Fix doc comment for coalescePartitions.parallelism…

…First

This changes the second `true` to `false` to make the doc comment correct. A setting of false will mean to not prioritize parallism and that will lead to less small tasks. Seems like it incorrectness was introduced here: apache#44787

### What changes were proposed in this pull request?

Documentation fix.

### Why are the changes needed?

Current doc is wrong.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

N/A

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes apache#45437 from eejbyfeldt/fix-minor-doc-comment-on-parallism-first.

Authored-by: Emil Ejbyfeldt <eejbyfeldt@liveintent.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -710,7 +710,7 @@ object SQLConf {
         "parallelism of the Spark cluster. The calculated size is usually smaller than the " +
         "configured target size. This is to maximize the parallelism and avoid performance " +
         "regressions when enabling adaptive query execution. It's recommended to set this " +
-        "config to true on a busy cluster to make resource utilization more efficient (not many " +
+        "config to false on a busy cluster to make resource utilization more efficient (not many " +
         "small tasks).")
       .version("3.2.0")
       .booleanConf