[Docs]: fix "Test with predefined time" sections in non-Node.js docs

[metametadata]

Page(s)

• https://playwright.dev/python/docs/clock#test-with-predefined-time
• https://playwright.dev/java/docs/clock#test-with-predefined-time
• https://playwright.dev/dotnet/docs/clock#test-with-predefined-time

Description

The mentioned sections contain only HTML, but they should also contain code snippets, the same as in docs for Node.js: https://playwright.dev/docs/clock#test-with-predefined-time.