login: Fix button inner alignment, for spinner
login: Fix button inner alignment, for spinner

Closes #13491
cockpituous/cockpit,moraleslazaro/cockpit,deryni/cockpit,deryni/cockpit,cockpit-project/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,garrett/cockpit,cockpituous/cockpit,mvollmer/cockpit,garrett/cockpit,mvollmer/cockpit,cockpituous/cockpit,cockpit-project/cockpit,mvollmer/cockpit,deryni/cockpit,deryni/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,garrett/cockpit,cockpit-project/cockpit,deryni/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,deryni/cockpit,garrett/cockpit,deryni/cockpit,moraleslazaro/cockpit,garrett/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,cockpit-project/cockpit,martinpitt/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,cockpituous/cockpit