rust: Disable rust oe-selftest

After rust is upgraded to 1.71 and later versions, the rust oe-selftest gives
build errors due to unstable nightly options(see the error mentioned below). Thus, disable the test suite
until the issue is fixed

error: the option `Z` is only accepted on the nightly compiler
thread 'main' panicked at 'failed to gather the target spec for x86_64-poky-linux-gnu', synthetic_targets.rs:66:9

Following issues are created in Yocto bugzilla and rust upstream to track this issue-

https://bugzilla.yoctoproject.org/show_bug.cgi?id=15275
rust-lang/rust#115642
https://users.rust-lang.org/t/does-rust-test-suite-supports-nightly-options-during-bootstrapping-in-rust/103108
https://users.rust-lang.org/t/unable-to-read-target-specs-when-rust-1-73-is-bootstrapped-in-yocto-poky/102959

(From OE-Core rev: 769e3f7e3871a375b1037dfb391e67876f987450)

Signed-off-by: Yash Shinde <Yash.Shinde@windriver.com>
Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

meta/lib/oeqa/selftest/cases/rust.py

@@ -39,6 +39,9 @@ def parse_results(filename):
 @OETestTag("runqemu")
 class RustSelfTestSystemEmulated(OESelftestTestCase, OEPTestResultTestCase):
     def test_rust(self, *args, **kwargs):
+        # Disable Rust Oe-selftest
+        self.skipTest("The Rust Oe-selftest is disabled.")
+
         # build remote-test-server before image build
         recipe = "rust"
         start_time = time.time()