RCORE-1984 update clang and prefer ARM64 to x86_64 (#7475)

Author: jbreams

CHANGELOG.md

@@ -56,6 +56,7 @@
 * Sha-2 is no longer required as a submodule on Windows if linking with OpenSSL.
 * The Catch2 submodule has moved to `test/external/catch`.
 * Fix possible file corruption if using Transaction::copy_to if nested collections are present.
+* Evergreen config was udpated so most linux CI testing is done on ubuntu 22.04 on aarch64 with clang 18, upgrading from clang 11 on ubuntu 20.04 mostly on x86_64 ([PR #7475](https://github.com/realm/realm-core/pull/7475)).
 
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