[Spark] Update tests in ConvertToDeltaSuite (delta-io#3635)

#### Which Delta project/connector is this regarding?


- [X] Spark
- [ ] Standalone
- [ ] Flink
- [ ] Kernel
- [ ] Other (fill in here)

## Description

Enable injection of special chars in temporary directories in two tests
in ConvertToDeltaSuite. The previous issues have been resolved in
90c1b2a.


## How was this patch tested?

Test-only change.

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

No

spark/src/test/scala/org/apache/spark/sql/delta/ConvertToDeltaSuiteBase.scala

@@ -188,7 +188,7 @@ trait ConvertToDeltaSuiteBase extends ConvertToDeltaSuiteBaseCommons
   }
 
   test("filter non-parquet file for schema inference when not using catalog schema") {
-    withTempDir(prefix = "spark") { dir =>
+    withTempDir { dir =>
       val tempDir = dir.getCanonicalPath
       writeFiles(tempDir + "/part=1/", Seq(1).toDF("corrupted_id"), format = "orc")
       writeFiles(tempDir + "/part=2/", Seq(2).toDF("id"))

spark/src/test/scala/org/apache/spark/sql/delta/HiveConvertToDeltaSuite.scala

@@ -130,7 +130,7 @@ abstract class HiveConvertToDeltaSuiteBase
 
   test("convert a Hive based external parquet table") {
     val tbl = "hive_parquet"
-    withTempDir(prefix = "spark") { dir =>
+    withTempDir { dir =>
       withTable(tbl) {
         sql(
           s"""