fix: harden traffic test-grant submit and search races

src/views/TrafficOpsView/TrafficOpsView.vue

@@ -774,7 +774,9 @@ let grantSearchSeq = 0
 async function searchGrantUsers(keyword) {
   const q = String(keyword || '').trim()
   if (!q) {
+    grantSearchSeq += 1
     grantUserOptions.value = []
+    grantUserSearching.value = false
     return
   }
   const seq = ++grantSearchSeq
@@ -822,6 +824,7 @@ function parseGrantBalanceText(data) {
 }
 
 async function submitGrant() {
+  if (grantSubmitting.value) return
   grantFormError.value = ''
   const userIdNum = Number(String(grantForm.userId || '').trim())
   const amountGb = Number(grantForm.amountGb)