Privacy: Convert buttons to links visually in Privacy Export/Erasure "Next Steps" column.

With a lot of export or erasure requests, the secondary buttons were becoming overwhelming when stacked on top of each other.

Props xkon, karmatosed.
Fixes #49323.
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git-svn-id: https://core.svn.wordpress.org/trunk@47047 1a063a9b-81f0-0310-95a4-ce76da25c4cd