Revert "Unset interpreter in TempDBTools as well"

This reverts commit 8b5446f.

Some ToolTacticsTests stopped working due to the original commit, as
discovered by Enguerrand. From what I can tell, the reason is the
following:

When the BelleInterpreter is unset (and thereby killed) after
interpreting is over, the registered TraceRecordingListener edits the
database at TraceRecordingListener.scala line 171.

This then results in the db.extractTactic call to fail to reconstruct
the tactic, and thus the test fails, e.g. at ToolTacticsTests.scala line
272.

I have no idea why db.extractTactic returns "Mathematica <function1>"
and similar instead of failing in a more obvious way.

keymaerax-webui/src/main/scala/edu/cmu/cs/ls/keymaerax/hydra/TempDBTools.scala

@@ -129,19 +129,11 @@ class TempDBTools(additionalListeners: Seq[IOListener]) {
       constructGlobalProvable = false,
     )
     val listeners = listener :: Nil ++ additionalListeners
-
-    val result =
-      try {
-        BelleInterpreter.setInterpreter(interpreter(listeners))
-        BelleInterpreter(t, BelleProvable.plain(ProvableSig.startProof(entry.model.asInstanceOf[Formula], entry.defs)))
-      } finally {
-        // The TraceRecordingListener has a reference to the db. When the interpreter is killed (e.g. by another call to
-        // BelleInterpreter.setInterpreter later), this can cause errors if the db has been closed in the meantime.
-        // Because of this, we unset (and thereby kill) the interpreter here while the db is still valid.
-        BelleInterpreter.unsetInterpreter()
-      }
-
-    result match {
+    BelleInterpreter.setInterpreter(interpreter(listeners))
+    BelleInterpreter(
+      t,
+      BelleProvable.plain(ProvableSig.startProof(entry.model.asInstanceOf[Formula], entry.defs)),
+    ) match {
       case BelleProvable(provable, _) =>
         assert(
           entry.defs.exhaustiveSubst(provable.conclusion) == expectedSubstConclusion,