Re-enable StyleCop warnings SA1028 and SA1518 (trailing whitespace and blank lines) (#40113)
Mechanical/automated change. The only manual changes were a) removing the two rules from the CodeAnalysis.ruleset file, b) removing spaces from one line of a .targets file that is used to generate a .cs file, and c) reverting the changes in a few test files where the naive replacement happened in the middle of a verbatim string where the whitespace actually mattered.
Signed-off-by: dotnet-bot <dotnet-bot@microsoft.com>