Should I commit release key store for Android app to team repository?

You should not.

Release keystore is the most sensitive data.

In my team, there is only one people can sign the release package. (And may be one for backing up).

All sensitive info MUST be ignored and we make a reference to these info.

In my team, we config like that:

On Android Studio:

/local.properties file:

storeFile=[path/to/keystore/file]
keyAlias=[alias's key]
keyPassword=[alias's password]
storePassword=[key's password]

/app/build.gradle, config scope:

signingConfigs {
  release {
    Properties properties = new Properties()
    properties.load(project.rootProject.file('local.properties').newDataInputStream())
    storeFile file(properties.getProperty('storeFile'))
    keyAlias properties.getProperty('keyAlias')
    storePassword properties.getProperty('storePassword')
    keyPassword properties.getProperty('keyPassword')
  }
}

buildTypes {
  release {
    minifyEnabled false
    proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    signingConfig signingConfigs.release
  }
  .
  .
  .
}

See my complete demo config:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 21
    buildToolsVersion "22.0.1"

    defaultConfig {
        multiDexEnabled = true

        applicationId "com.appconus.demoapp"
        minSdkVersion 16
        targetSdkVersion 21
        multiDexEnabled = true
        versionCode 18
        versionName "1.3"
    }

    signingConfigs {
        release {
            Properties properties = new Properties()
            properties.load(project.rootProject.file('local.properties').newDataInputStream())
            storeFile file(properties.getProperty('storeFile'))
            keyAlias properties.getProperty('keyAlias')
            storePassword properties.getProperty('storePassword')
            keyPassword properties.getProperty('keyPassword')
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            signingConfig signingConfigs.release
        }
        debug {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
        applicationVariants.all { variant ->
            appendVersionNameVersionCode(variant, defaultConfig)
        }
    }
}
dependencies {
    compile 'com.google.android.gms:play-services:8.1.0'
}