Semaphore: remove manual Go installation, expedite 'cache restore'

'sem-version' apparently installs Go, so rely on it instead of isntalling
Go manually.

Execute 'cache restore' after 'checkout' (since it scans for go.mod), but
before 'go install' to avoid tar errors unpacking the cache archive:

```
Unpacking command failed: tar: /home/semaphore/go/pkg/mod/github.com/jonboulle/clockwork@v0.2.2/.github/workflows/ci.yml: Cannot open: File exists
tar: /home/semaphore/go/pkg/mod/github.com/jonboulle/clockwork@v0.2.2/.github/workflows/.editorconfig: Cannot open: File exists
tar: /home/semaphore/go/pkg/mod/github.com/jonboulle/clockwork@v0.2.2/ticker.go: Cannot open: File exists
...
```

'go install' does something that changes the ownership of go/pkg/mod,
tripping up tar. Since 'go install' doesn't need to be run outside of a Go
module like 'go get' did when using it to install tool binaries, it can
safely be run after checkout.

Signed-off-by: Timo Beckers <timo@isovalent.com>

.semaphore/semaphore.yml

@@ -23,14 +23,13 @@ blocks:
       prologue:
         commands:
           - sudo sh -c 'swapoff -a && fallocate -l 2G /swapfile && chmod 0600 /swapfile && mkswap /swapfile && swapon /swapfile'
-          - sudo mkdir -p /usr/local/golang/1.19 && curl -fL "https://go.dev/dl/go1.19.1.linux-amd64.tar.gz" | sudo tar -xz -C /usr/local/golang/1.19
-          - sem-version go 1.19
+          - sem-version go 1.19.1
           - export PATH="$PATH:$(go env GOPATH)/bin"
-          - curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.48.0
-          - go install gotest.tools/gotestsum@v1.8.1
           - checkout
           - cache restore
           - go mod tidy
+          - curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.48.0
+          - go install gotest.tools/gotestsum@v1.8.1
           - sudo pip3 install https://github.com/amluto/virtme/archive/beb85146cd91de37ae455eccb6ab67c393e6e290.zip
           - sudo apt-get update
           - sudo apt-get install -y --no-install-recommends qemu-system-x86 clang-9 llvm-9