feat: Add docker reproducible builds (#6799)

Which issue # does this PR address?

This PR addresses reproducible builds. The current dockerfile builds the lighthouse binary but not reproducibly.
You can verify that by following these steps:
```
docker build --no-cache --output=. .
mv usr/local/bin/lighthouse lighthouse1
rm usr/local/bin/lighthouse
docker build --no-cache --output=. .
mv usr/local/bin/lighthouse lighthouse2
sha256sum lighthouse1 lighthouse2
```
You will notice that each one of the binaries has a different checksum upon each build. This is critical for systems that depends on requiring reproducible builds, such as running lighthouse in confidential computing, like Intel TDX.


  This PR adds a new build profile as well as a Dockerfile.reproducible that enables building the lighthouse binary reproducibly.
By following the steps I listed above, you will be able to verify that the resulted binary has the same hash upon several subsequent builds for the same version.

How to test it:
```
mkdir output1 output2
docker build --no-cache -f Dockerfile.reproducible --output=output1 .
docker build --no-cache -f Dockerfile.reproducible --output=output2 .
sha256sum output1/lighthouse output2/lighthouse
# hashes should be identical
rm -rf output1 output2
```

Cargo.toml

@@ -298,5 +298,12 @@ lto = "fat"
 codegen-units = 1
 incremental = false
 
+[profile.reproducible]
+inherits = "release"
+debug = false
+panic = "abort"
+codegen-units = 1
+overflow-checks = true
+
 [patch.crates-io]
 quick-protobuf = { git = "https://github.com/sigp/quick-protobuf.git", rev = "681f413312404ab6e51f0b46f39b0075c6f4ebfd" }