fix(openchallenges): change paginator variable to dynamic rendering

[rrchai]

• fixes [Bug] search bar on search pages failed #2425

As we added a new condition to not the paginator element if no data found, the variable of paginator is undefined initially as it is static, which caused the error ^.

Changelogs

• Change the paginator to dynamic, so its value will be set after the content is fully initialized
• Use PrimeNG built-in property alwaysShow=false to hide the paginator when there is only one page
• Update page index on paginator UI once the pageNumber of param in a pasted url presents
• Disable the pageSize changes from the pasted url

[rrchai]

Noticed two new bugs a new bug related to the search pages:

• Copy & paste the pagination in url does not reflect the page number changes on the paginator UI. For example, entering http://localhost:4200/challenge?pageNumber=6 should show page number 7, but it stays page number 1.

• There are some "Upcoming" challenges in the result, but selecting "Upcoming" status filter shows no results not reproduced today after the changes