[Pix] Add metrics to Pix flow (8)

Add metrics regarding InitiatePayment call:
1. Add a PayflowExitedReason if InitiatePayment failed.
2. Remove the InitiatePayment result and transaction result histogram;
3. Add a histogram to record InitiatePayment call attempt;
4. Update InitiatePayment latency histogram to add a result breakdown.

go/payments-autofill-uma has been updated

OBSOLETE_HISTOGRAM[FacilitatedPayments.Pix.InitiatePayment.Result]=Replaced by FacilitatedPayments.{FacilitatedPaymentsType}.InitiatePayment.{Result}.Latency.
OBSOLETE_HISTOGRAM[FacilitatedPayments.Pix.InitiatePayment.Latency]=Replaced by FacilitatedPayments.{FacilitatedPaymentsType}.InitiatePayment.{Result}.Latency.

go/pix-in-chrome-metrics-revised

Bug: 367751320,377126728,378539918
Change-Id: I2138387775c9c4aa04063cc644d81b28e187e2d7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6003429
Reviewed-by: Vishwas Uppoor <vishwasuppoor@google.com>
Commit-Queue: Siyu An <siyua@chromium.org>
Reviewed-by: Rouslan Solomakhin <rouslan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1381934}