Drop redundant rustup overrides when we just installed

There's no reason to set the default toolchain when we just
installed the toolchain. Also, for some reason this now fails since
the `$PATH` isn't updated by the installer in the same shell so
`rustup` isn't found.

Author: TheBlueMatt

.github/workflows/build.yml

@@ -21,7 +21,6 @@ jobs:
       - name: Install Rust stable toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain stable
-          rustup override set stable
       - name: Run externalized tests
         run: |
           cd ext-functional-test-demo
@@ -43,7 +42,6 @@ jobs:
       - name: Install Rust ${{ matrix.toolchain }} toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain ${{ matrix.toolchain }}
-          rustup override set ${{ matrix.toolchain }}
       - name: Install no-std-check dependencies for ARM Embedded
         if: "matrix.platform == 'self-hosted'"
         run: |
@@ -77,7 +75,6 @@ jobs:
       - name: Install Rust ${{ matrix.toolchain }} toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain ${{ matrix.toolchain }}
-          rustup override set ${{ matrix.toolchain }}
       - name: Set RUSTFLAGS to deny warnings
         if: "matrix.toolchain == '1.75.0'"
         run: echo "RUSTFLAGS=-D warnings" >> "$GITHUB_ENV"
@@ -150,7 +147,6 @@ jobs:
       - name: Install Rust ${{ env.TOOLCHAIN }} toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain ${{ env.TOOLCHAIN }}
-          rustup override set ${{ env.TOOLCHAIN }}
       - name: Cache routing graph snapshot
         id: cache-graph
         uses: actions/cache@v4
@@ -217,7 +213,6 @@ jobs:
       - name: Install Rust ${{ env.TOOLCHAIN }} toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain ${{ env.TOOLCHAIN }}
-          rustup override set ${{ env.TOOLCHAIN }}
       - name: Fetch full tree and rebase on upstream
         run: |
           git remote add upstream https://github.com/lightningdevkit/rust-lightning
@@ -240,7 +235,6 @@ jobs:
       - name: Install Rust ${{ env.TOOLCHAIN }} toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain ${{ env.TOOLCHAIN }}
-          rustup override set ${{ env.TOOLCHAIN }}
       - name: Run cargo check for release build.
         run: |
           cargo check --release
@@ -267,7 +261,6 @@ jobs:
       - name: Install Rust ${{ env.TOOLCHAIN }} toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain ${{ env.TOOLCHAIN }}
-          rustup override set ${{ env.TOOLCHAIN }}
       - name: Install dependencies for honggfuzz
         run: |
           sudo apt-get update
@@ -295,7 +288,6 @@ jobs:
       - name: Install Rust ${{ env.TOOLCHAIN }} toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain ${{ env.TOOLCHAIN }}
-          rustup override set ${{ env.TOOLCHAIN }}
       - name: Install clippy
         run: |
           rustup component add clippy
@@ -313,7 +305,6 @@ jobs:
       - name: Install Rust ${{ env.TOOLCHAIN }} toolchain
         run: |
           curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain ${{ env.TOOLCHAIN }}
-          rustup override set ${{ env.TOOLCHAIN }}
       - name: Install rustfmt
         run: |
           rustup component add rustfmt