Refactor count_bugs to use libmozdata

[suhaibmujahid]

We should use the Bugzilla class from libmozdata.bugzilla instead of doing a direct request:

bugbug/bugbug/bugzilla.py

Lines 282 to 291 in 082613f

	def count_bugs(bug_query_params):
	bug_query_params["count_only"] = 1
	r = utils.get_session("bugzilla").get(
	"https://bugzilla.mozilla.org/rest/bug", params=bug_query_params
	)
	r.raise_for_status()
	count = r.json()["bug_count"]
	return count

Example:

bugbug/bugbug/bugzilla.py

Line 110 in 082613f

Bugzilla(params, bughandler=bughandler).get_data().wait()

[akshayamadhuri]

@suhaibmujahid i would like to work on this issue can you help me with this

[suhaibmujahid]

@akshayamadhuri you are welcom to work on the issue! You can start by following the instructions in Guidance for first contributors.