event queue: Don't set a minimum for lifespan_secs.
event queue: Don't set a minimum for lifespan_secs.

This makes it more convenient for developers to set very short values
for this (e.g. 1 minute) for the purposes of testing/debugging; there
aren't obvious problems with letting users set short values for this.

showell/zulip,synicalsyntax/zulip,rht/zulip,hackerkid/zulip,shubhamdhama/zulip,synicalsyntax/zulip,punchagan/zulip,brainwane/zulip,brainwane/zulip,punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,dhcrzf/zulip,rht/zulip,dhcrzf/zulip,synicalsyntax/zulip,dhcrzf/zulip,eeshangarg/zulip,andersk/zulip,dhcrzf/zulip,timabbott/zulip,hackerkid/zulip,timabbott/zulip,shubhamdhama/zulip,rishig/zulip,punchagan/zulip,shubhamdhama/zulip,showell/zulip,kou/zulip,rishig/zulip,punchagan/zulip,timabbott/zulip,punchagan/zulip,dhcrzf/zulip,dhcrzf/zulip,punchagan/zulip,tommyip/zulip,shubhamdhama/zulip,jackrzhang/zulip,showell/zulip,hackerkid/zulip,rht/zulip,rht/zulip,tommyip/zulip,hackerkid/zulip,andersk/zulip,zulip/zulip,shubhamdhama/zulip,zulip/zulip,eeshangarg/zulip,andersk/zulip,tommyip/zulip,shubhamdhama/zulip,timabbott/zulip,timabbott/zulip,showell/zulip,showell/zulip,zulip/zulip,tommyip/zulip,eeshangarg/zulip,hackerkid/zulip,kou/zulip,brainwane/zulip,tommyip/zulip,hackerkid/zulip,jackrzhang/zulip,rht/zulip,eeshangarg/zulip,synicalsyntax/zulip,eeshangarg/zulip,rht/zulip,punchagan/zulip,jackrzhang/zulip,andersk/zulip,kou/zulip,andersk/zulip,rishig/zulip,brainwane/zulip,synicalsyntax/zulip,shubhamdhama/zulip,brainwane/zulip,zulip/zulip,tommyip/zulip,synicalsyntax/zulip,rishig/zulip,brainwane/zulip,jackrzhang/zulip,kou/zulip,dhcrzf/zulip,jackrzhang/zulip,jackrzhang/zulip,zulip/zulip,hackerkid/zulip,rishig/zulip,showell/zulip,timabbott/zulip,andersk/zulip,zulip/zulip,kou/zulip,showell/zulip,timabbott/zulip,tommyip/zulip,brainwane/zulip,kou/zulip,rishig/zulip,synicalsyntax/zulip,jackrzhang/zulip,rht/zulip,andersk/zulip,kou/zulip,zulip/zulip,rishig/zulip