join ops before in format (#6370)

when there are several subscribers, i get: 

```
 thread '...' (7476) panicked at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/itertools-0.14.0/src/format.rs:95:21:
    Format: was already formatted once
    stack backtrace:
       0: std::panicking::begin_panic
                 at /rustc/c23ed3ef28b3cc30658310f771ddc66e5b687cf4/library/std/src/panicking.rs:762:5
       1: <itertools::format::Format<core::slice::iter::Iter<alloc::string::String>>>::format
                 at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/itertools-0.14.0/src/format.rs:95:21
       2: <itertools::format::Format<core::slice::iter::Iter<alloc::string::String>> as core::fmt::Display>::fmt
                 at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/itertools-0.14.0/src/format.rs:119:26
       3: core::fmt::rt::Argument::fmt
                 at /rustc/c23ed3ef28b3cc30658310f771ddc66e5b687cf4/library/core/src/fmt/rt.rs:152:76
       4: core::fmt::write
       5: <&dyn core::fmt::Debug as core::fmt::Debug>::fmt
                 at /home/runner/.rustup/toolchains/nightly-2025-11-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/fmt/mod.rs:2865:62
       6: core::fmt::rt::Argument::fmt
                 at /rustc/c23ed3ef28b3cc30658310f771ddc66e5b687cf4/library/core/src/fmt/rt.rs:152:76
       7: core::fmt::write
       8: <&mut tracing_subscriber::fmt::format::escape::EscapingWriter as core::fmt::Write::write_fmt::SpecWriteFmt>::spec_write_fmt
                 at /home/runner/.rustup/toolchains/nightly-2025-11-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/fmt/mod.rs:236:21
       9: <tracing_subscriber::fmt::format::escape::EscapingWriter as core::fmt::Write>::write_fmt
                 at /home/runner/.rustup/toolchains/nightly-2025-11-24-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/fmt/mod.rs:241:14
      10: <tracing_subscriber::fmt::format::escape::Escape<&dyn core::fmt::Debug> as core::fmt::Debug>::fmt
                 at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tracing-subscriber-0.3.22/src/fmt/format/escape.rs:42:9
      11: core::fmt::rt::Argument::fmt
                 at /rustc/c23ed3ef28b3cc30658310f771ddc66e5b687cf4/library/core/src/fmt/rt.rs:152:76
      12: core::fmt::write
      13: <&mut alloc::string::String as core::fmt::Write::write_fmt::SpecWriteFmt>::spec_write_fmt
```

---------

Signed-off-by: blaginin <github@blaginin.me>

Author: blaginin

vortex-array/src/executor.rs

@@ -7,7 +7,6 @@ use std::fmt::Display;
 use std::sync::Arc;
 use std::sync::atomic::AtomicUsize;
 
-use itertools::Itertools;
 use vortex_error::VortexResult;
 use vortex_session::VortexSession;
 
@@ -116,8 +115,21 @@ impl Display for ExecutionCtx {
 
 impl Drop for ExecutionCtx {
     fn drop(&mut self) {
-        if !self.ops.is_empty() {
-            tracing::debug!("exec[{}] trace:\n{}", self.id, self.ops.iter().format("\n"));
+        if !self.ops.is_empty() && tracing::enabled!(tracing::Level::DEBUG) {
+            // Unlike itertools `.format()` (panics in 0.14 on second format)
+            struct FmtOps<'a>(&'a [String]);
+            impl Display for FmtOps<'_> {
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    for (i, op) in self.0.iter().enumerate() {
+                        if i > 0 {
+                            f.write_str("\n")?;
+                        }
+                        f.write_str(op)?;
+                    }
+                    Ok(())
+                }
+            }
+            tracing::debug!("exec[{}] trace:\n{}", self.id, FmtOps(&self.ops));
         }
     }
 }