remove unneeded fragment block

[tanhauhau]

• remove slot template fragment block
  • in fix render fallback slot content due to white space #4500 we do not use the fragment block if it is empty, but we still render the fragment block code.
• remove empty slot fallback block
  • if the slot fallback has no content, remove it.

[tanhauhau]

CI error:

 * [new tag]         v3.9.2                -> v3.9.2
git checkout --progress --force 58d3628d5cbc8b56f6dee9ab1552f632951fca8d
##[error]fatal: reference is not a tree: 58d3628d5cbc8b56f6dee9ab1552f632951fca8d
Removed matchers: 'checkout-git'
##[error]Git checkout failed with exit code: 128
##[error]Exit code 1 returned from process: file name '/home/runner/runners/2.165.2/bin/Runner.PluginHost', arguments 'action "GitHub.Runner.Plugins.Repository.v1_0.CheckoutTask, Runner.Plugins"'.

it seemed like when it failed like this, i need to push a new commit hash to force the CI to run correctly again

[Conduitry]

Is there an issue or bug that this is intended to fix, or is it an optimization?

[tanhauhau]

It's an optimisation