[CI] Temporarily disable Rust toolchain installation. #1138

Job	Run time
C++ Xcode (macOS)	1m 5s
C++ Clang 13 (Ubuntu 24.04)	1m 54s
C++ Clang 9 (Ubuntu 20.04)	1m 35s
C++ Clang 14 (Ubuntu 24.04)	1m 30s
C++ Clang 10 (Ubuntu 20.04)	1m 41s
C++ Clang 15 (Ubuntu 24.04)	1m 29s
C++ GCC 6 (Ubuntu 20.04)	1m 38s
C++ Clang 11 (Ubuntu 20.04)	1m 43s
C++ Clang 16 (Ubuntu 24.04)	1m 29s
C++ GCC 7 (Ubuntu 20.04)	1m 35s
C++ Clang 12 (Ubuntu 20.04)	1m 40s
C++ Clang 17 (Ubuntu 24.04)	1m 27s
C++ GCC 8 (Ubuntu 20.04)	1m 43s
C++ Clang 18 (Ubuntu 24.04)	1m 27s
C++ GCC 9 (Ubuntu 20.04)	1m 40s
C++ GCC 10 (Ubuntu 20.04)	1m 37s
C++ GCC 11 (Ubuntu 24.04)	1m 43s
C++ MSVC (Windows) (windows-latest)	6m 15s
C++ GCC 12 (Ubuntu 24.04)	1m 35s
C# 8.0.x	2m 55s
C++ GCC 13 (Ubuntu 24.04)	1m 30s
Golang 1.22.x	1m 51s
C++ GCC 14 (Ubuntu 24.04)	1m 35s
Rust stable	1m 14s
Rust beta	51s
Rust nightly	1m 0s
Java 17 (ubuntu-24.04)	1m 45s
Java 17 (windows-latest)	3m 9s
Java 17 (macos-latest)	1m 17s
Java 21 (ubuntu-24.04)	2m 4s
Java 21 (windows-latest)	3m 31s
Java 21 (macos-latest)	1m 23s
	58m 51s

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