[docs] Fix table formatting in history-based-optimization.rst

[steveburnett]

Description

New error in local doc build:

/Users/steveburnett/Documents/GitHub/presto/presto-docs/src/main/sphinx/optimizer/history-based-optimization.rst:34: ERROR: Malformed table. Column span alignment problem in table line 3.

and

build succeeded, 20 warnings.

Motivation and Context

Fixes one error in the doc build because the table is incorrectly formatted.

Impact

Documentation.

Test Plan

Local doc builds.

Before fix:

/Users/steveburnett/Documents/GitHub/presto/presto-docs/src/main/sphinx/optimizer/history-based-optimization.rst:34: ERROR: Malformed table. Column span alignment problem in table line 3.

and

build succeeded, 20 warnings.

After fix:

ERROR: Malformed table. does not appear.

build succeeded, 19 warnings.

Contributor checklist

• Please make sure your submission complies with our development, formatting, commit message, and attribution guidelines.
• PR description addresses the issue accurately and concisely. If the change is non-trivial, a GitHub Issue is referenced.
• Documented new properties (with its default value), SQL syntax, functions, or other functionality.
• If release notes are required, they follow the release notes guidelines.
• Adequate tests were added if applicable.
• CI passed.

Release Notes

== NO RELEASE NOTE ==

[steveburnett]

This has also been fixed in #23335.