Unify colons in UI

[xufeiranfree]

Category

This change is exactly one of the following (please change [ ] to [x]) to indicate which:

• a bug fix (Fix #...)
• a new Ripper
• a refactoring
• a style change/fix
• a new feature

Description

When start app, there will be double colons after "Maxmum download threads" in some languages, I fixed it.
"Maximum download threads", "Timeout', "Retry download count" are similar settings, with a lable and an input, but it is not same in different languages, some of them end without a colon. Overall, inconsistency, I modified them to be consistent.

Testing

Required verification:

• I've verified that there are no regressions in mvn test (there are no new failures or errors).
• I've verified that this change works as intended.
  • Downloads all relevant content.
  • Downloads content from multiple pages (as necessary or appropriate).
  • Saves content at reasonable file names (e.g. page titles or content IDs) to help easily browse downloaded content.
• I've verified that this change did not break existing functionality (especially in the Ripper I modified).

Optional but recommended:

• I've added a unit test to cover my change.