Fix: overwrite text-align of the table title in markdown

What does this MR do and why?

Related issue: #411542 (closed)

The table cell in title from markdown has been add the align property, but style has been overwrite by file bootstrap/scss/_reboot.scss

This MR is add some style to overwrite the text-align of the table title in markdown, to make it be same with DOM align property

/cc @prajnamas @x-- @JeremyWuuuuu @qk44077907

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How to set up and validate locally

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1. Open or create a project
2. Enter project issues list
3. Create a issue
4. Enter Demo code into Description

| Default Header | Left Align | Right Align | Center Align |
| --- | :-- | --: | :-: |
| xxxxxxxxxxxxxxxxxx | xxxxxxxxxxxxxxxxxx | xxxxxxxxxxxxxxxxxx | xxxxxxxxxxxxxxxxxx |
| xxx | xxx | xxx | xxx |

5. Save the issue
6. See the table in description

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