Revert "Added API to set ephemeral port allocator range."
**- What I did**

Since commit 2c4a868f64e6e13bf06589a6670122196651e82e, Docker doesn't
use the value of net.ipv4.ip_local_port_range when choosing an ephemeral
port. This change reverts back to the previous behavior.

Fixes #43054.

**- How to verify it**

1. `make shell`
2. In the container, `sysctl -w net.ipv4.ip_local_port_range="39000 40000"`
3. Start dockerd
4. Run `docker run --rm -it -p 80 nginx`
5. Check what port Docker has picked with `docker ps`

**- Description for the changelog**

`Use the value of net.ipv4.ip_local_port_range when choosing an ephemeral port`
libnetwork/portallocator/portallocator_unix.go
//go:build !windows
// +build !windows

package portallocator

const (
	// defaultPortRangeStart indicates the first port in port range
	defaultPortRangeStart = 49153
	// defaultPortRangeEnd indicates the last port in port range
	// consistent with default /proc/sys/net/ipv4/ip_local_port_range
	// upper bound on linux
	defaultPortRangeEnd = 60999
)

//go:build !windows
// +build !windows

package portallocator

const (
	// defaultPortRangeStart indicates the first port in port range
	defaultPortRangeStart = 49153
	// defaultPortRangeEnd indicates the last port in port range
	// consistent with default /proc/sys/net/ipv4/ip_local_port_range
	// upper bound on linux
	defaultPortRangeEnd = 65535
)

Let me comment on this line; this may have been related to https://github.com/moby/moby/pull/40055#issuecomment-1145398915 as well (in case we need to un-revert this change in range)

/cc @neersighted @corhere @evol262 

(and myself, for if this causes havoc in our products 🙈)