OOM When downloading chunks from external storage

[Dartoxian]

Similar to #154 , I am seeing an OOM in ExternalStorageService when downloading chunks.

> found a local restoring point
check health status: 0 correct, 234 missing and 0 faulty files
  * Downloading data/data-633695bf-1eeb-48b8-9abb-f2cb25ce43b7/00001-XBQAigzp4k4ejeS: ok
  * Downloading data/data-633695bf-1eeb-48b8-9abb-f2cb25ce43b7/00002-P1lRAfjTdEdgMLN: ok
  * Downloading data/data-633695bf-1eeb-48b8-9abb-f2cb25ce43b7/00003-SssVfinoaucsON4: ok
  * Downloading data/data-633695bf-1eeb-48b8-9abb-f2cb25ce43b7/00004-YQdjRyRzAAORR5Z: ^C^C
^CPHP Fatal error:  Allowed memory size of 1048576000 bytes exhausted (tried to allocate 139810392 bytes) in /var/www/html/custom_apps/backup/lib/Service/ExternalFolderService.php on line 296

I am running nextcloud 23.0.2 and backup 1.0.4 - I am also running this as a hotfix https://github.com/nextcloud/backup/pull/204

[kds69]

+1 Maybe it can help someone = I could manage to make backup recovery work despite OOM issue, having taken below mitigations: -switch my 2GB RPi with a 4GB RPi -increase swap file to 2GB -clonel OS from a 16Go SD card to a 32Go SD card (+extending partition w GPart on a VM Linux runing on my Windows 10...)