[TBDGen] Re-enable tests (#70766)

Now that Xcode has been updated on builders (#69485), these tests should pass.

Author: cyndyishida

test/IRGen/virtual-function-elimination-two-modules.swift

@@ -1,6 +1,3 @@
-// FIXME: Disabled due to https://github.com/apple/swift/issues/69485
-// REQUIRES: issue_69485
-
 // Tests that under -enable-llvm-vfe + -internalize-at-link, cross-module
 // virtual calls are done via thunks and LLVM GlobalDCE is able to remove unused
 // virtual methods from a library based on a list of used symbols by a client.

test/IRGen/witness-method-elimination-two-modules.swift

@@ -1,6 +1,3 @@
-// FIXME: Disabled due to https://github.com/apple/swift/issues/69485
-// REQUIRES: issue_69485
-
 // Tests that under -enable-llvm-wme + -internalize-at-link, cross-module
 // witness method calls are done via thunks and LLVM GlobalDCE is able to remove
 // unused witness methods from a library based on a list of used symbols by a

test/TBD/linking-with-tbd.swift

@@ -1,6 +1,3 @@
-// FIXME: Disabled due to https://github.com/apple/swift/issues/69485
-// REQUIRES: issue_69485
-
 // REQUIRES: VENDOR=apple
 // REQUIRES: executable_test