fix: Don't static link agent binary (FIPS requirement)

[svghadi]

The static link flag in the Makefile is causing downstream build failures, as we cannot build static binaries for FIPS. In the agent Makefile, the -static flag is forced, which prevents it from being overridden when calling the make target from the Dockerfile.

We need to allow overriding LDFLAGS so that the -static flag can be removed or skipped. One way to achieve this is by dropping the override at https://github.com/argoproj-labs/argocd-agent/blob/840b84916eea783f3f0c9208ab31b770b55aaa84/Makefile#L64.
This would allow us to supply LDFLAGS from the CLI while still benefiting from the next override statement that adds the version information.

For now, I have reverted the change made in #620.

[svghadi]

Failure logs for a static build

    github.com/argoproj-labs/argocd-agent/principal/registration
  github.com/argoproj-labs/argocd-agent/principal/apis/eventstream
  github.com/argoproj-labs/argocd-agent/agent
  github.com/argoproj-labs/argocd-agent/principal/apis/auth
  github.com/argoproj-labs/argocd-agent/principal
  github.com/argoproj-labs/argocd-agent/cmd/argocd-agent
  # github.com/argoproj-labs/argocd-agent/cmd/argocd-agent
  /usr/lib/golang/pkg/tool/linux_amd64/link: running gcc failed: exit status 1
  /usr/bin/gcc -m64 -Wl,-z,now -Wl,-z,nocopyreloc -Wl,--build-id=0x10f70f367127f3ab3649cab44380b06a267f8c59 -o $WORK/b001/exe/a.out -static -Wl,--compress-debug-sections=zlib /tmp/go-link-4108206518/go.o /tmp/go-link-4108206518/000000.o /tmp/go-link-4108206518/000001.o /tmp/go-link-4108206518/000002.o /tmp/go-link-4108206518/000003.o /tmp/go-link-4108206518/000004.o /tmp/go-link-4108206518/000005.o /tmp/go-link-4108206518/000006.o /tmp/go-link-4108206518/000007.o /tmp/go-link-4108206518/000008.o /tmp/go-link-4108206518/000009.o /tmp/go-link-4108206518/000010.o /tmp/go-link-4108206518/000011.o /tmp/go-link-4108206518/000012.o /tmp/go-link-4108206518/000013.o /tmp/go-link-4108206518/000014.o /tmp/go-link-4108206518/000015.o /tmp/go-link-4108206518/000016.o /tmp/go-link-4108206518/000017.o /tmp/go-link-4108206518/000018.o /tmp/go-link-4108206518/000019.o /tmp/go-link-4108206518/000020.o /tmp/go-link-4108206518/000021.o /tmp/go-link-4108206518/000022.o /tmp/go-link-4108206518/000023.o /tmp/go-link-4108206518/000024.o /tmp/go-link-4108206518/000025.o /tmp/go-link-4108206518/000026.o /tmp/go-link-4108206518/000027.o /tmp/go-link-4108206518/000028.o /tmp/go-link-4108206518/000029.o /tmp/go-link-4108206518/000030.o /tmp/go-link-4108206518/000031.o /tmp/go-link-4108206518/000032.o /tmp/go-link-4108206518/000033.o /tmp/go-link-4108206518/000034.o /tmp/go-link-4108206518/000035.o /tmp/go-link-4108206518/000036.o /tmp/go-link-4108206518/000037.o /tmp/go-link-4108206518/000038.o /tmp/go-link-4108206518/000039.o /tmp/go-link-4108206518/000040.o /tmp/go-link-4108206518/000041.o /tmp/go-link-4108206518/000042.o /tmp/go-link-4108206518/000043.o /tmp/go-link-4108206518/000044.o /tmp/go-link-4108206518/000045.o /tmp/go-link-4108206518/000046.o /tmp/go-link-4108206518/000047.o /tmp/go-link-4108206518/000048.o /tmp/go-link-4108206518/000049.o /tmp/go-link-4108206518/000050.o /tmp/go-link-4108206518/000051.o -O2 -g -lresolv -O2 -g -lpthread -O2 -g -O2 -g -ldl -pthread -O2 -g -ldl -no-pie -static
  /usr/bin/ld: cannot find -lresolv
  /usr/bin/ld: have you installed the static version of the resolv library ?
  /usr/bin/ld: cannot find -lc
  /usr/bin/ld: have you installed the static version of the c library ?
  collect2: error: ld returned 1 exit status
  
  make: *** [Makefile:189: argocd-agent] Error 1
  subprocess exited with status 2
  subprocess exited with status 2
  Error: building at STEP "RUN . /cachi2/cachi2.env &&     CGO_ENABLED=1 GOEXPERIMENT=strictfipsruntime     GO_TAGS=strictfipsruntime GO_MOD=mod     make argocd-agent BIN_NAME_AGENT=argocd-agent": exit status 2