generate_test_data: Remove some useless type annotations.
generate_test_data: Remove some useless type annotations.

One of these caused a parser error trying to run pyre on Zulip; the
other is just useless as the type can be inferred.

kou/zulip,shubhamdhama/zulip,rht/zulip,kou/zulip,shubhamdhama/zulip,synicalsyntax/zulip,synicalsyntax/zulip,eeshangarg/zulip,hackerkid/zulip,rht/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip,kou/zulip,punchagan/zulip,timabbott/zulip,eeshangarg/zulip,brainwane/zulip,shubhamdhama/zulip,timabbott/zulip,zulip/zulip,andersk/zulip,brainwane/zulip,kou/zulip,timabbott/zulip,showell/zulip,zulip/zulip,eeshangarg/zulip,eeshangarg/zulip,timabbott/zulip,synicalsyntax/zulip,timabbott/zulip,shubhamdhama/zulip,punchagan/zulip,timabbott/zulip,rht/zulip,brainwane/zulip,synicalsyntax/zulip,showell/zulip,rht/zulip,showell/zulip,hackerkid/zulip,kou/zulip,brainwane/zulip,hackerkid/zulip,andersk/zulip,brainwane/zulip,kou/zulip,punchagan/zulip,synicalsyntax/zulip,zulip/zulip,showell/zulip,shubhamdhama/zulip,eeshangarg/zulip,timabbott/zulip,kou/zulip,zulip/zulip,hackerkid/zulip,eeshangarg/zulip,hackerkid/zulip,showell/zulip,brainwane/zulip,brainwane/zulip,punchagan/zulip,shubhamdhama/zulip,eeshangarg/zulip,andersk/zulip,andersk/zulip,andersk/zulip,zulip/zulip,andersk/zulip,showell/zulip,hackerkid/zulip,synicalsyntax/zulip,zulip/zulip,synicalsyntax/zulip,showell/zulip,punchagan/zulip,rht/zulip,zulip/zulip,punchagan/zulip,shubhamdhama/zulip,rht/zulip