daemon: raise default minimum API version to v1.44

- relates to 96b29f5a1f
- similar to 08e4e88482

The daemon currently provides support for API versions all the way back
to v1.24, which is the version of the API that shipped with docker 1.12.0
(released in 2016).

Such old versions of the client are rare, and supporting older API versions
has accumulated significant amounts of code to remain backward-compatible
(which is largely untested, and a "best-effort" at most).

This patch updates the minimum API version to v1.44, matching the minimum
version of the client, and matching the API version of docker v25.0, which
is the oldest supported version (through Mirantis MCR).

The intent is to start deprecating older API versions when daemons implementing
them reach EOL. This patch does not yet remove backward-compatibility code
for older API versions, and the DOCKER_MIN_API_VERSION environment variable
allows overriding the minimum version (to allow restoring the behavior from
before this patch), however, API versions below v1.44 should be considered
"best effort", and we may remove compatibility code to provide "degraded"
support.

With this patch the daemon defaults to API v1.44 as minimum:

    docker version
    Client:
     Version:           28.5.0
     API version:       1.51
     Go version:        go1.24.7
     Git commit:        887030f
     Built:             Thu Oct  2 14:54:39 2025
     OS/Arch:           linux/arm64
     Context:           default

    Server:
     Engine:
      Version:          dev
      API version:      1.52 (minimum version 1.44)
    ....

Trying to use an older version of the API produces an error:

    DOCKER_API_VERSION=1.43 docker version
    Client:
     Version:           28.5.0
     API version:       1.43 (downgraded from 1.51)
     Go version:        go1.24.7
     Git commit:        887030f
     Built:             Thu Oct  2 14:54:39 2025
     OS/Arch:           linux/arm64
     Context:           default
    Error response from daemon: client version 1.43 is too old. Minimum supported API version is 1.44, please upgrade your client to a newer version

To restore the previous minimum, users can start the daemon with the
DOCKER_MIN_API_VERSION environment variable set:

    DOCKER_MIN_API_VERSION=1.24 dockerd

API 1.24 is the oldest supported API version;

    docker version
    Client:
     Version:           28.5.0
     API version:       1.24 (downgraded from 1.51)
     Go version:        go1.24.7
     Git commit:        887030f
     Built:             Thu Oct  2 14:54:39 2025
     OS/Arch:           linux/arm64
     Context:           default

    Server:
     Engine:
      Version:          dev
      API version:      1.52 (minimum version 1.24)
    ....

When using the `DOCKER_MIN_API_VERSION` with a version of the API that
is not supported, an error is produced when starting the daemon;

    DOCKER_MIN_API_VERSION=1.23 dockerd --validate
    invalid DOCKER_MIN_API_VERSION: minimum supported API version is 1.24: 1.23

    DOCKER_MIN_API_VERSION=1.99 dockerd --validate
    invalid DOCKER_MIN_API_VERSION: maximum supported API version is 1.52: 1.99

Specifying a malformed API version also produces the same error;

    DOCKER_MIN_API_VERSION=hello dockerd --validate
    invalid DOCKER_MIN_API_VERSION: minimum supported API version is 1.24: hello

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

integration/networking/mac_addr_test.go

@@ -146,7 +146,7 @@ func TestInspectCfgdMAC(t *testing.T) {
 
 	ctx := setupTest(t)
 
-	d := daemon.New(t)
+	d := daemon.New(t, daemon.WithEnvVars("DOCKER_MIN_API_VERSION=1.43"))
 	d.StartWithBusybox(ctx, t)
 	defer d.Stop(t)
 
@@ -241,7 +241,7 @@ func TestWatchtowerCreate(t *testing.T) {
 
 	ctx := setupTest(t)
 
-	d := daemon.New(t)
+	d := daemon.New(t, daemon.WithEnvVars("DOCKER_MIN_API_VERSION=1.25"))
 	d.StartWithBusybox(ctx, t)
 	defer d.Stop(t)