[Tests] Disable backtracing in some tests.

These tests can be negatively affected by the warnings about unsupported
Swift backtracer settings.

rdar://144497613

Author: al45tair

test/ModuleInterface/ModuleCache/module-cache-diagnostics.swift

@@ -1,5 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: %empty-directory(%t/modulecache)
+// RUN: export SWIFT_BACKTRACE=
 
 // rdar://88830153
 // https://github.com/apple/swift/issues/58134

test/remote-run/exit-code.test-sh

@@ -1,5 +1,6 @@
 REQUIRES: shell
 
+RUN: export SWIFT_BACKTRACE=
 RUN: not %debug-remote-run false >%t.txt 2>%t.errs.txt
 RUN: test -f %t.txt -a ! -s %t.txt
 RUN: test -f %t.errs.txt -a ! -s %t.errs.txt

validation-test/BuildSystem/swift-xcodegen.test

@@ -3,6 +3,7 @@
 # RUN: %empty-directory(%t/out)
 # RUN: export PATH="%original_path_env"
 # RUN: export SWIFTCI_USE_LOCAL_DEPS=1
+# RUN: export SWIFT_BACKTRACE=
 
 # REQUIRES: OS=macosx
 # REQUIRES: standalone_build

validation-test/Python/line-directive.swift

@@ -1,5 +1,6 @@
 // RUN: %empty-directory(%t)
 // RUN: split-file %s %t
+// RUN: export SWIFT_BACKTRACE=
 
 // RUN: %{python} %utils/line-directive
 // RUN: %{python} %utils/line-directive -- %{python} %t/unicode.py

validation-test/Python/update_checkout.swift

@@ -4,5 +4,6 @@
 // than once for each supported Apple device.
 
 // REQUIRES: OS=macosx
+// RUN: export SWIFT_BACKTRACE=
 
 // RUN: %{python} %utils/update_checkout/run_tests.py