miri test: Disable new unsupported tests (#32104)

Seen in
https://buildkite.com/materialize/nightly/builds/11711#0196084e-eaa8-4f23-8321-b063630a71ce

Follow-up to #32083

### Checklist

- [ ] This PR has adequate test coverage / QA involvement has been duly
considered. ([trigger-ci for additional test/nightly
runs](https://trigger-ci.dev.materialize.com/))
- [ ] This PR has an associated up-to-date [design
doc](https://github.com/MaterializeInc/materialize/blob/main/doc/developer/design/README.md),
is a design doc
([template](https://github.com/MaterializeInc/materialize/blob/main/doc/developer/design/00000000_template.md)),
or is sufficiently small to not require a design.
  <!-- Reference the design in the description. -->
- [ ] If this PR evolves [an existing `$T ⇔ Proto$T`
mapping](https://github.com/MaterializeInc/materialize/blob/main/doc/developer/command-and-response-binary-encoding.md)
(possibly in a backwards-incompatible way), then it is tagged with a
`T-proto` label.
- [ ] If this PR will require changes to cloud orchestration or tests,
there is a companion cloud PR to account for those changes that is
tagged with the release-blocker label
([example](MaterializeInc/cloud#5021)).
<!-- Ask in #team-cloud on Slack if you need help preparing the cloud
PR. -->
- [ ] If this PR includes major [user-facing behavior
changes](https://github.com/MaterializeInc/materialize/blob/main/doc/developer/guide-changes.md#what-changes-require-a-release-note),
I have pinged the relevant PM to schedule a changelog post.

---------

Signed-off-by: Moritz Hoffmann <mh@materialize.com>
Co-authored-by: Moritz Hoffmann <mh@materialize.com>

Author: def-

src/expr-derive-impl/src/lib.rs

@@ -54,6 +54,7 @@ pub fn test_sqlfunc_str(attr: &str, item: &str) -> (String, String) {
 mod test {
     use quote::quote;
 
+    #[cfg_attr(miri, ignore)] // unsupported operation: extern static `pidfd_spawnp` is not supported by Miri
     #[mz_ore::test]
     fn insta_test_add_int16() {
         let attr = quote! {
@@ -75,6 +76,7 @@ mod test {
         insta::assert_snapshot!("add_int16", output, &input);
     }
 
+    #[cfg_attr(miri, ignore)] // unsupported operation: extern static `pidfd_spawnp` is not supported by Miri
     #[mz_ore::test]
     fn insta_test_unary() {
         let attr = quote! {};
@@ -87,6 +89,7 @@ mod test {
         insta::assert_snapshot!("unary_fn", output, &input);
     }
 
+    #[cfg_attr(miri, ignore)] // unsupported operation: extern static `pidfd_spawnp` is not supported by Miri
     #[mz_ore::test]
     fn insta_test_unary_arena() {
         let attr = quote! {};
@@ -99,6 +102,7 @@ mod test {
         insta::assert_snapshot!("unary_arena_fn", output, &input);
     }
 
+    #[cfg_attr(miri, ignore)] // unsupported operation: extern static `pidfd_spawnp` is not supported by Miri
     #[mz_ore::test]
     fn insta_test_unary_ref() {
         let attr = quote! {};
@@ -111,6 +115,7 @@ mod test {
         insta::assert_snapshot!("unary_ref", output, &input);
     }
 
+    #[cfg_attr(miri, ignore)] // unsupported operation: extern static `pidfd_spawnp` is not supported by Miri
     #[mz_ore::test]
     fn insta_test_complex_output_type() {
         let attr = quote! {
@@ -129,6 +134,7 @@ mod test {
         insta::assert_snapshot!("complex_type", output, &input);
     }
 
+    #[cfg_attr(miri, ignore)] // unsupported operation: extern static `pidfd_spawnp` is not supported by Miri
     #[mz_ore::test]
     fn insta_test_binary_arena() {
         let attr = quote! {};

src/expr-derive-impl/src/sqlfunc.rs

@@ -84,6 +84,7 @@ fn generate_test(attr: TokenStream, item: TokenStream, name: &Ident) -> TokenStr
 
     quote! {
         #[cfg(test)]
+        #[cfg_attr(miri, ignore)] // unsupported operation: extern static `pidfd_spawnp` is not supported by Miri
         #[mz_ore::test]
         fn #test_name() {
             let (output, input) = mz_expr_derive_impl::test_sqlfunc_str(#attr, #item);