Update unit test CI to install torch using pip (pytorch#2604)

Summary:
Pull Request resolved: pytorch#2604

Moving away from conda install for TorchRec CI, which atalman suggests

Reviewed By: sarckk

Differential Revision: D66708069

fbshipit-source-id: 33d38f1cb204fae1d3f80c14e9be3591d03d8696

.github/workflows/pyre.yml

@@ -19,7 +19,7 @@ jobs:
         uses: actions/checkout@v2
       - name: Install dependencies
         run: >
-          conda install --yes pytorch cpuonly -c pytorch-nightly &&
+          pip install torch --index-url https://download.pytorch.org/whl/nightly/cpu &&
           pip install fbgemm-gpu --index-url https://download.pytorch.org/whl/nightly/cpu &&
           pip install -r requirements.txt &&
           pip install pyre-check-nightly==$(cat .pyre_configuration | grep version | awk '{print $2}' | sed 's/\"//g')

.github/workflows/unittest_ci.yml

@@ -73,13 +73,15 @@ jobs:
         conda info
         python --version
         conda run -n build_binary python --version
-        conda install -n build_binary \
-          --yes \
-          pytorch pytorch-cuda=11.8 -c pytorch-nightly -c nvidia
+        conda run -n build_binary \
+          pip install torch --index-url https://download.pytorch.org/whl/nightly/${{ matrix.cuda-tag }}
+        conda run -n build_binary \
+          python -c "import torch"
+        echo "torch succeeded"
         conda run -n build_binary \
           python -c "import torch.distributed"
         conda run -n build_binary \
-          pip install fbgemm-gpu --index-url https://download.pytorch.org/whl/nightly/cu118
+          pip install fbgemm-gpu --index-url https://download.pytorch.org/whl/nightly/${{ matrix.cuda-tag }}
         conda run -n build_binary \
           python -c "import fbgemm_gpu"
         echo "fbgemm_gpu succeeded"

.github/workflows/unittest_ci_cpu.yml

@@ -45,9 +45,11 @@ jobs:
         conda info
         python --version
         conda run -n build_binary python --version
-        conda install -n build_binary \
-          --yes \
-          pytorch cpuonly -c pytorch-nightly
+        conda run -n build_binary \
+          pip install torch --index-url https://download.pytorch.org/whl/nightly/cpu
+        conda run -n build_binary \
+          python -c "import torch"
+        echo "torch succeeded"
         conda run -n build_binary \
           python -c "import torch.distributed"
         conda run -n build_binary \