Secrets uid not set when using --mount

There appears to be a regression in docker buildx. I updated to the latest version available in the docker Ubuntu repos before submitting this.

When writing --mount=type=secret,uid=1000,gid=1000,id=pqpi_password I would expect that the user be set on the secret file file in the container when building. On the latest version it is not. However on a older version it is.

--- Linux ---
[deploy_base  8/15] RUN --mount=type=secret,uid=1000,gid=1000,id=pqpi_username --mount=type=secret,uid=1000,gid=1000,id=pqpi_password   ls -n /run/secrets   && id   && exit 1
0.325 total 8
0.325 -r-------- 1 0 1000 16 Feb 23 08:27 pqpi_password
0.325 -r-------- 1 0 1000 25 Feb 23 08:27 pqpi_username
0.286 uid=1000(service_user) gid=1000(service_user) groups=1000(service_user)

docker version
Client: Docker Engine - Community
 Version:           23.0.1
 API version:       1.42
 Go version:        go1.19.5
 Git commit:        a5ee5b1
 Built:             Thu Feb  9 19:47:01 2023
 OS/Arch:           linux/amd64
 Context:           default

Server: Docker Engine - Community
 Engine:
  Version:          23.0.1
  API version:      1.42 (minimum version 1.12)
  Go version:       go1.19.5
  Git commit:       bc3805a
  Built:            Thu Feb  9 19:47:01 2023
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.6.18
  GitCommit:        2456e983eb9e37e47538f59ea18f2043c9a73640
 runc:
  Version:          1.1.4
  GitCommit:        v1.1.4-0-g5fd4c4d
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

--- Mac ---
[deploy_base  8/15] RUN --mount=type=secret,id=pqpi_username,uid=1000 --mount=type=secret,id=pqpi_password,uid=1000 ls -n /run/secrets && exit 1
0.349 total 8
0.349 -r-------- 1 1000 0 15 Feb 23 08:48 pqpi_password
0.349 -r-------- 1 1000 0 26 Feb 23 08:48 pqpi_username
ERROR: executor failed running [/bin/sh -c ls -n /run/secrets && exit 1  /helpers/docker-setup-pqpi-auth.sh   && /helpers/docker-pip-install.sh   && rm -rf $HOME/.netrc]: exit code: 1


docker version
Client:
 Cloud integration: v1.0.29
 Version:           20.10.22
 API version:       1.41
 Go version:        go1.18.9
 Git commit:        3a2c30b
 Built:             Thu Dec 15 22:28:41 2022
 OS/Arch:           darwin/amd64
 Context:           default
 Experimental:      true

Server: Docker Desktop 4.16.2 (95914)
 Engine:
  Version:          20.10.22
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.18.9
  Git commit:       42c8b31
  Built:            Thu Dec 15 22:26:14 2022
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.6.14
  GitCommit:        9ba4b250366a5ddde94bb7c9d1def331423aa323
 runc:
  Version:          1.1.4
  GitCommit:        v1.1.4-0-g5fd4c4d
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

I am aware that it's linux native and docker desktop that I am submitting here. But its what I had available to diagnose the issue.

Reproduce the regression with the reported Dockerfile RUN --mount=type=secret example, comparing the Linux Docker 23.0.1 result with the older and macOS results. Start from the secret-mount handling used by that entry point, then add a regression test; done means the secret file's uid and gid match the requested values.