v4.0: fix(fs): align write size to 4096 to support all NVMEs (backport of #11335)

[mergify]

Problem

#9856 ended up with 512 alignment for direct I/O writes, but it fails for some NVMEs. As reported in FD tests:

Archive error: failed to unpack "accounts/316628658.54075": IO error: Invalid argument (os error 22)

The used hardware spec:

Node                  Generic               SN                   Model                                    Namespace  Usage                      Format           FW Rev
--------------------- --------------------- -------------------- ---------------------------------------- ---------- -------------------------- ---------------- --------
..
/dev/nvme1n1          /dev/ng1n1            KND7N5364I1308G1S    DELL NVME ISE PE8110 RI U.2 960GB        0x1        960.20  GB / 960.20  GB      4 KiB +  0 B   1.1.0

indicates the NVME sector size of 4KiB, which ends up as required alignment for O_DIRECT

independently there were failures noticed on some CI workers where disks are

$ lsblk -o NAME,SIZE,LOG-SEC,PHY-SEC,MOUNTPOINT
NAME          SIZE LOG-SEC PHY-SEC MOUNTPOINT
nvme2n1       3.5T    4096    4096
└─vg01-lv01   7.4T    4096    4096 /var/lib/buildkite-agent
nvme0n1     447.1G     512    4096
├─nvme0n1p1     1M     512    4096
└─nvme0n1p2 447.1G     512    4096 /
nvme3n1       3.5T    4096    4096
└─vg01-lv01   7.4T    4096    4096 /var/lib/buildkite-agent
nvme1n1     447.1G    4096    4096
└─vg01-lv01   7.4T    4096    4096 /var/lib/buildkite-agent

Again: LOG-SEC column showing 4096 makes it match the same cause and bumping alignment to 4096 is confirmed to fix the issue there.

Summary of Changes

Bump constant used for alignment of writes to 4096 and update comment.

---

This is an automatic backport of pull request #11335 done by [Mergify](https://mergify.com).

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.0%. Comparing base (0775041) to head (6322b81).

Additional details and impacted files

@@           Coverage Diff           @@
##             v4.0   #11424   +/-   ##
=======================================
  Coverage    83.0%    83.0%           
=======================================
  Files         838      838           
  Lines      316433   316433           
=======================================
+ Hits       262803   262806    +3     
+ Misses      53630    53627    -3     

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