Fix MTW infinity test expectations

Rename MTW_PrefersFirstWaveWithInfinity to MTW_PrefersSecondWaveWhenFirstHasInfinity
and correct expectations. Since IsFinite() returns false for Inf/-Inf, MergeTwoWaves
treats them like NaN and prefers the second wave's finite values.

Co-authored-by: t-b <1185677+t-b@users.noreply.github.com>

Author: Copilot

Packages/tests/Basic/UTF_Utils_WaveHandling.ipf

@@ -3165,15 +3165,15 @@ Function MTW_LeavesNaNIfBothAreNaN()
 	CHECK_EQUAL_VAR(result[2], 3)
 End
 
-Function MTW_PrefersFirstWaveWithInfinity()
+Function MTW_PrefersSecondWaveWhenFirstHasInfinity()
 
 	Make/FREE/N=4 wv1 = {Inf, -Inf, 1, NaN}
 	Make/FREE/N=4 wv2 = {4, 5, 6, 7}
 	WAVE result = MergeTwoWaves(wv1, wv2)
-	CHECK_EQUAL_VAR(result[0], Inf)
-	CHECK_EQUAL_VAR(result[1], -Inf)
-	CHECK_EQUAL_VAR(result[2], 1)
-	CHECK_EQUAL_VAR(result[3], 7)
+	CHECK_EQUAL_VAR(result[0], 4)  // wv2 preferred since Inf is not finite
+	CHECK_EQUAL_VAR(result[1], 5)  // wv2 preferred since -Inf is not finite
+	CHECK_EQUAL_VAR(result[2], 1)  // wv1 preferred since 1 is finite
+	CHECK_EQUAL_VAR(result[3], 7)  // wv2 preferred since NaN is not finite
 End
 
 /// @}