Speed up threaded-cursor spec by ~1.8s

The "should safely close cursors in threaded environment" example in
spec/plsql/schema_spec.rb spawns two threads that call
DBMS_SESSION.sleep (or DBMS_LOCK.sleep on pre-18c) and joins them.
The point of the test is that two concurrent calls on the same
connection don't trip the cursor pool — the sleep durations are only
there to keep both calls in flight at once.

The original 1- and 2-second sleeps dominated the suite at ~2.05s
out of ~10s total (~21%, the slowest example by a wide margin).
Drop them to 0.1s and 0.2s, which still gives 100ms of
guaranteed-overlap and a 100ms ordering gap between the two threads
— far more than OS scheduling needs to keep both in flight. Verified
stable across three back-to-back runs at ~0.29s each.

Net effect: full suite drops from ~9.93s to ~8.08s (~19% faster);
this example moves from #1 to rsim#4 in the slowest-examples profile.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yahonda

spec/plsql/schema_spec.rb

@@ -255,14 +255,14 @@ class TestModel < TestBaseModel
   it "should safely close cursors in threaded environment" do
     if (plsql.connection.database_version <=> [18, 0, 0, 0]) >= 0
       expect {
-        t1 = Thread.new { plsql.dbms_session.sleep(1) }.tap { |t| t.abort_on_exception = true }
-        t2 = Thread.new { plsql.dbms_session.sleep(2) }.tap { |t| t.abort_on_exception = true }
+        t1 = Thread.new { plsql.dbms_session.sleep(0.1) }.tap { |t| t.abort_on_exception = true }
+        t2 = Thread.new { plsql.dbms_session.sleep(0.2) }.tap { |t| t.abort_on_exception = true }
         [t2, t1].each { |t| t.join }
       }.not_to raise_error
     else
       expect {
-        t1 = Thread.new { plsql.dbms_lock.sleep(1) }.tap { |t| t.abort_on_exception = true }
-        t2 = Thread.new { plsql.dbms_lock.sleep(2) }.tap { |t| t.abort_on_exception = true }
+        t1 = Thread.new { plsql.dbms_lock.sleep(0.1) }.tap { |t| t.abort_on_exception = true }
+        t2 = Thread.new { plsql.dbms_lock.sleep(0.2) }.tap { |t| t.abort_on_exception = true }
         [t2, t1].each { |t| t.join }
       }.not_to raise_error
     end