fix(query): fix unique function NULL value not hashable handling

enh: default ep set

enh: opt index mutex

fix: vnode pre-process

test：add test case for functions

test: modify case

TD-16034

docs: refine image alt text

test:add cluster testcase of electing leader and python connector using statement api

test: modify sleep value

feat(tmq): drop cgroup

Rewrote some sentences for readability.

Changed to: "In the above sample, `print_result` is used to simplify the printing of the result set. It is similar to `taos_use_result`"

feat: add tag version

Stylistic changes.
Clarifying changes.
Removed reference to taos_use_result since it is not mentioned in code snippet.

Minor changes for spelling and style.

Stylistic and grammar changes.

Grammar changes.

Spelling correction.

Spelling correction
Stylistic changes

Some stylistic changes.
Some clarifying changes.

Added best practices for firewall and data protections.
Added explicit hostnames (fqdn) in cluster set up examples for clarity.

Minor grammar, edits, and phrasing for the Admin > Problem Diagnostics page.