Update RNTester snapshots

Summary:
The iOS snapshots have been out of date for months, but the failure was not caught in open source's  `test_objc` job because `xcpretty` was swallowing the non-zero error code.

To fix this, I enabled recording mode in RNTesterSnapshotTests.m temporarily, and re-ran the tests in order to update the snapshots. I've also switched the test device used by Circle CI to iPhone 6s to be consistent with the snapshot tests that run internally at Facebook.

Integration tests are not fully fixed yet, but I can confirm the following tests are fixed by this diff:

```
-[RNTesterIntegrationTests testImageSnapshotTest]
-[RNTesterIntegrationTests testSimpleSnapshotTest]
-[RNTesterSnapshotTests testARTExample]
-[RNTesterSnapshotTests testLayoutExample]
-[RNTesterSnapshotTests testSliderExample]
-[RNTesterSnapshotTests testSwitchExample]
-[RNTesterSnapshotTests testTabBarExample]
-[RNTesterSnapshotTests testTextExample]
-[RNTesterSnapshotTests testViewExample]
```

I've also fixed a few shellcheck warnings in related scripts.

Reviewed By: fkgozali

Differential Revision: D13506865

fbshipit-source-id: dab985130c2ff3cb9dea19d1f87c8ee65d8c141e

scripts/.tests.env

@@ -18,7 +18,7 @@ export AVD_ABI=x86
 
 ## IOS ##
 export IOS_TARGET_OS="12.1"
-export IOS_DEVICE="iPhone XS"
+export IOS_DEVICE="iPhone 6s"
 export TVOS_DEVICE="Apple TV"
 
 ## CI OVERRIDES ##

scripts/launchPackager.command

@@ -5,11 +5,13 @@
 # LICENSE file in the root directory of this source tree.
 
 # Set terminal title
-echo -en "\033]0;Metro Bundler\a"
+echo -en "\\033]0;Metro Bundler\\a"
 clear
 
 THIS_DIR=$(cd -P "$(dirname "$(readlink "${BASH_SOURCE[0]}" || echo "${BASH_SOURCE[0]}")")" && pwd)
+
+# shellcheck source=/dev/null
 . "$THIS_DIR/packager.sh"
 
 echo "Process terminated. Press <enter> to close the window"
-read
+read -r

scripts/packager.sh

@@ -5,6 +5,8 @@
 # LICENSE file in the root directory of this source tree.
 
 THIS_DIR=$(cd -P "$(dirname "$(readlink "${BASH_SOURCE[0]}" || echo "${BASH_SOURCE[0]}")")" && pwd)
+
+# shellcheck source=/dev/null
 source "${THIS_DIR}/.packager.env"
-cd "$THIS_DIR/.."
+cd "$THIS_DIR/.." || exit
 node "./cli.js" start "$@"