[seekdb][build] Remove obsolete embedded and lite build modes

[hnwyllmm]

Task Description

BUILD_EMBED_MODE maintained a separate compile-time product variant together with obsolete in-process Embed APIs and native Arrow/Parquet support. OB_BUILD_LITE and OB_BUILD_OBSERVER_LITE were configurable despite their false paths being stale or empty.

Solution Description

• Keep BUILD_EMBED_MODE as a deprecated no-op compatibility option and make release_embedded use the same build arguments as release.
• Preserve runtime seekdb --embedded behavior through ObServer::embedded_, including Unix socket, telemetry, client auto-exit, and an explicit PALF FetchLogEngine startup option.
• Remove the old C/Python/JNI Embed APIs, embedded client, wheel/APK packaging, sqlite benchmark, and native Arrow/Parquet code and dependencies.
• Return error 1235 for Parquet outfile requests while keeping CSV/ODPS/ORC enum values stable and retaining Java ODPS arrowTable mode.
• Fix static libgomp_static.a linkage, standardize former compile-time branches, and keep the embedded KV-cache bucket sizing.
• Collapse OB_BUILD_LITE and OB_BUILD_OBSERVER_LITE to their effective true behavior and remove the obsolete macros and false branches.

Passed Regressions

• release, release_embedded, and release -DBUILD_EMBED_MODE=ON builds passed; normalized compile and link graphs are identical.
• Affected release_no_unity objects compiled independently.
• PALF FetchLogEngine disabled tests passed (4/4); KV-cache bucket test passed (1/1).
• Normal mode TCP/SQL and FetchLogEngine startup smoke passed.
• Embedded Unix-socket SQL, disabled FetchLogEngine, client auto-exit, and restart recovery smoke passed.
• CSV outfile succeeded; Parquet returned 1235 without creating a file.
• VSAG/HNSW index creation and four concurrent approximate queries passed.
• Final ELF has static GOMP symbols and no DT_NEEDED libgomp.so.
• git diff --check and cached diff checks passed.

Upgrade Compatibility

Runtime seekdb --embedded semantics remain compatible. The removed in-process Embed API and Parquet SQL capability are intentionally no longer supported; persisted Parquet format metadata is treated as unsupported without migration.

Other Information

This MR contains only commit b34b70375fc. The unrelated local untracked file 2 is not included. Documentation is intentionally unchanged.

Release Note

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