ios build [nfc]: Remove more remnants of tvOS.

Done to follow the template-app change in
facebook/react-native@216037757, on the path to the RN v0.64
upgrade.

ios/ZulipMobile.xcodeproj/project.pbxproj

@@ -39,7 +39,6 @@
 		CFA67D1F1EC23BCB0070048E /* UtilManager.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = UtilManager.m; path = ZulipMobile/UtilManager.m; sourceTree = "<group>"; };
 		CFA67D211EC23BDD0070048E /* UtilManager.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = UtilManager.h; path = ZulipMobile/UtilManager.h; sourceTree = "<group>"; };
 		ED297162215061F000B7C4FE /* JavaScriptCore.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = JavaScriptCore.framework; path = System/Library/Frameworks/JavaScriptCore.framework; sourceTree = SDKROOT; };
-		ED2971642150620600B7C4FE /* JavaScriptCore.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = JavaScriptCore.framework; path = Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS12.0.sdk/System/Library/Frameworks/JavaScriptCore.framework; sourceTree = DEVELOPER_DIR; };
 		FB0511DD408657240F6D4EA3 /* Pods-ZulipMobile.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-ZulipMobile.debug.xcconfig"; path = "Target Support Files/Pods-ZulipMobile/Pods-ZulipMobile.debug.xcconfig"; sourceTree = "<group>"; };
 /* End PBXFileReference section */