[SPARK-41131][SQL] Improve error message for `UNRESOLVED_MAP_KEY.WITH…

…OUT_SUGGESTION`

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

This PR proposes to improve error message for `UNRESOLVED_MAP_KEY.WITHOUT_SUGGESTION`.

### Why are the changes needed?

Printing the single quotes in error message as an example would more helpful for users, and we don't need 'please' in the error message. See https://spark.apache.org/error-message-guidelines.html more detail.

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

Minor error message improvement.

From
```
Cannot resolve column `col1` as a map key. If the key is a string literal, please add single quotes around it.
```

To
```
Cannot resolve column `col1` as a map key. If the key is a string literal, add single quotes '' around it.
```

### How was this patch tested?

The existing CI should pass.

Closes apache#38646 from itholic/SPARK-41131.

Authored-by: itholic <[email protected]>
Signed-off-by: Max Gekk <[email protected]>

core/src/main/resources/error/error-classes.json

@@ -1157,7 +1157,7 @@
   },
   "UNRESOLVED_MAP_KEY" : {
     "message" : [
-      "Cannot resolve column <objectName> as a map key. If the key is a string literal, please add single quotes around it."
+      "Cannot resolve column <objectName> as a map key. If the key is a string literal, add the single quotes '' around it."
     ],
     "subClass" : {
       "WITHOUT_SUGGESTION" : {