Rollup merge of #119628 - RalfJung:duplicate-test, r=compiler-errors

remove duplicate test

This was added in ace6fc3646 where overflowing-rsh-6 differed from overflowing-rsh-5 in a feature gate, but the feature has since been stabilized, making the tests 100% identical.

Most of these tests in numbers-arithmetic could be put into one file rather than having so many files that all test the same lint... but it doesn't seem worth the effort. After https://github.com/rust-lang/rust/pull/119432 we might be able to remove most of them entirely as they will be covered by the new tests added there.

tests/ui/numbers-arithmetic/overflowing-rsh-6.rs

@@ -1,9 +0,0 @@
-// build-fail
-// compile-flags: -C debug-assertions
-
-#![deny(arithmetic_overflow)]
-
-fn main() {
-    let _n = 1i64 >> [64][0];
-    //~^ ERROR: this arithmetic operation will overflow
-}

tests/ui/numbers-arithmetic/overflowing-rsh-6.stderr

@@ -1,14 +0,0 @@
-error: this arithmetic operation will overflow
-  --> $DIR/overflowing-rsh-6.rs:7:14
-   |
-LL |     let _n = 1i64 >> [64][0];
-   |              ^^^^^^^^^^^^^^^ attempt to shift right by `64_i32`, which would overflow
-   |
-note: the lint level is defined here
-  --> $DIR/overflowing-rsh-6.rs:4:9
-   |
-LL | #![deny(arithmetic_overflow)]
-   |         ^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 1 previous error
-