autotest: fold DoRepositionTerrain settle delays into condition waits

The flat 'terrain altitude to settle' delays immediately preceded a
wait_altitude with minimum_duration=10, which already proves settled
terrain-relative altitude.  Remove the flat delays and grow the wait
timeouts by the same amount so the total allowance is unchanged and
the wait exits as soon as altitude has genuinely settled.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Tools/autotest/quadplane.py

@@ -2686,13 +2686,11 @@ class AutoTestQuadPlane(vehicle_test_suite.TestSuite):
             timeout=600,
             height_accuracy=None,  # dest.alt is above-terrain; alt checked below
         )
-        self.delay_sim_time(20, reason="terrain altitude to settle")
-
         self.wait_altitude(
             dest.alt-10,  # NOTE: reuse of alt from abovE
             dest.alt+10,  # use a 10m buffer as the plane needs to go up and down a bit to maintain terrain distance
             minimum_duration=10,
-            timeout=30,
+            timeout=50,  # includes time for the terrain altitude to settle
             relative=False,
             altitude_source="TERRAIN_REPORT.current_height"
         )
@@ -2749,12 +2747,11 @@ class AutoTestQuadPlane(vehicle_test_suite.TestSuite):
                 timeout=600,
                 height_accuracy=None,  # loc.alt is above-terrain; alt checked below
             )
-            self.delay_sim_time(10, reason="terrain altitude to settle")
             self.wait_altitude(
                 loc.alt-5,
                 loc.alt+5,
                 minimum_duration=10,
-                timeout=30,
+                timeout=40,  # includes time for the terrain altitude to settle
                 relative=False,
                 altitude_source="TERRAIN_REPORT.current_height"
             )
@@ -2846,12 +2843,11 @@ class AutoTestQuadPlane(vehicle_test_suite.TestSuite):
                 timeout=600,
                 height_accuracy=None,  # loc.alt is above-terrain; alt checked below
             )
-            self.delay_sim_time(10, reason="terrain altitude to settle")
             self.wait_altitude(
                 loc.alt-5,
                 loc.alt+5,
                 minimum_duration=10,
-                timeout=30,
+                timeout=40,  # includes time for the terrain altitude to settle
                 relative=False,
                 altitude_source="TERRAIN_REPORT.current_height"
             )