Consolidate query planning examples (#18142)

[cj-zhukov]

Which issue does this PR close?

• part of #Reduce the number of distinct binaries to reduce CI / compile time #18142.

Rationale for this change

This PR is for consolidating all the query_planning examples (analyzer_rule, expr_api, optimizer_rule, parse_sql_expr, plan_to_sql, planner_api, pruning, thread_pools) into a single example binary. We are agreed on the pattern and we can apply it to the remaining examples

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[cj-zhukov]

High-Level Overview

This PR consolidates all query_planning examples (analyzer_rule, expr_api, optimizer_rule, parse_sql_expr, plan_to_sql, planner_api, pruning, thread_pools) into a single example binary.
Previously, each example had its own file, but now they can be executed via subcommands using:

cargo run --example query_planning -- [analyzer_rule|expr_api|optimizer_rule|parse_sql_expr|plan_to_sql|planner_api|pruning|thread_pools]

[comphead]

Thanks @cj-zhukov