chore(toolchain): switch to stable Rust 1.96.1 and remove all nightly feature gates

Move the workspace from the pinned nightly-2026-03-21 to stable
1.96.1 and drop all 23 '#![feature]' gates across 13 crates,
rewriting the still-unstable API usages with stable equivalents:

- try_blocks: closures / an async block (table, query, common-function, servers)
- duration_constructors: Duration::from_secs(n * 86400) / (n * 60)
- iterator_try_collect: collect::<Result<Vec<_>, _>>()
- box_patterns: as_deref() + matches! chains (sql)
- error_iter: error_chain_root() source-chain walker (common-error);
  sources() includes the error itself, so the walker never panics
- int_roundings: div_floor -> div_euclid (equal for positive divisors)
- iter_partition_in_place: stable sort_by_key partition helper (index)
- hash_set_entry: HashSet::insert bool / contains+insert
- trait_alias: lifetime-parameterized dyn FnOnce type aliases (puffin)
- string_from_utf8_lossy_owned: from_utf8_lossy(&v).into_owned()
- never_type: Infallible (common-recordbatch)
- debug_closure_helpers: closure-backed DebugFmt newtype (mito2)
- binary_heap_pop_if: peek().is_some_and() + pop()
- exclusive_wrapper: drop Exclusive; C: Send + Unpin already in bounds
- stmt_expr_attributes: stale gate, no usages

Also fix release-dev-builder-images.yaml, which parsed
rust-toolchain.toml with a date-only regex and would produce empty
image versions with a stable channel; it now extracts the full
channel token. Dev-builder images verified against stable 1.96.1
(image build, default-toolchain behavior, binstall/nextest, riscv64
and android targets, in-image cargo check).

Validated on 1.96.1: cargo check --workspace --all-targets, clippy
--workspace --all-targets --all-features -D warnings, cargo fmt
--check, and nextest on all 13 affected crates (4586 passed).

Part of #9289. Depends on #9298 (fuzz nightly quarantine) merging
first.

Signed-off-by: Ning Sun <sunning@greptime.com>

.github/workflows/release-dev-builder-images.yaml

@@ -59,7 +59,10 @@ jobs:
           commitShortSHA=`echo ${{ github.sha }} | cut -c1-8`
           buildTime=`date +%Y%m%d%H%M%S`
           BUILD_VERSION="$commitShortSHA-$buildTime"
-          RUST_TOOLCHAIN_VERSION=$(cat rust-toolchain.toml | grep -Eo '[0-9]{4}-[0-9]{2}-[0-9]{2}')
+          # Extract the full channel string (e.g. "1.96.1" or
+          # "nightly-2026-03-21") so the image version always carries the
+          # toolchain it was built with.
+          RUST_TOOLCHAIN_VERSION=$(grep -E '^channel' rust-toolchain.toml | cut -d'"' -f2)
           IMAGE_VERSION="${RUST_TOOLCHAIN_VERSION}-${BUILD_VERSION}"
           echo "VERSION=${IMAGE_VERSION}" >> $GITHUB_ENV
           echo "version=$IMAGE_VERSION" >> $GITHUB_OUTPUT