prevent sync modal from forcing focus when switching inputs

[cezaraugusto]

fix #11653

Test Plan:

1. Go to sync panel
2. Open "I have an existing Sync code"
3. Autofocus should be in the passphrase textarea
4. Clicking on "Enter an optional name for this device" should focus correctly
5. close modal, go to "I am new to Sync"
6. Input should have autofocus as well

[cezaraugusto]

fyi issue happens because input for device name is reused in both modals causing autoFocus to conflict.

Also removed React lifecycle in favor of HTML to avoid wasting update calls.

[codecov-io]

Codecov Report

Merging #12783 into master will increase coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master   #12783      +/-   ##
==========================================
+ Coverage   56.09%    56.1%   +<.01%     
==========================================
  Files         279      279              
  Lines       27307    27303       -4     
  Branches     4443     4442       -1     
==========================================
  Hits        15318    15318              
+ Misses      11989    11985       -4

Flag	Coverage Δ
#unittest	56.1% <0%> (ø)	⬆️

Impacted Files	Coverage Δ
app/renderer/components/preferences/syncTab.js	17.36% <0%> (+0.35%)	⬆️

[diracdeltas]

test plan works!

[cezaraugusto]

Thanks!