[esp32] increase default stack size

[gjc13]

Problem

The stack overflows when running PASE pairing after the operational credentials change.

Summary of Changes

Increase the default stack size to 8192.

[github-actions]

Size increase report for "esp32-example-build" from 8a51de2

File	Section	File	VM
chip-all-clusters-app.elf	.flash.text	-4	-4

Full report output

BLOAT REPORT

Files found only in the build output:
    report.csv

Comparing ./master_artifact/chip-pigweed-app.elf and ./pull_artifact/chip-pigweed-app.elf:

sections,vmsize,filesize

Comparing ./master_artifact/chip-all-clusters-app.elf and ./pull_artifact/chip-all-clusters-app.elf:

sections,vmsize,filesize
.debug_loc,0,4
.flash.text,-4,-4

[dhrishi]

@gjc13 Is crypto (mbedTLS) used with the recent changes related to operational credentials? If yes, we prefer/suggest keeping the stack size as minimum 8KB. LGTM